Datasets:
aid stringlengths 9 15 | mid stringlengths 7 10 | abstract stringlengths 78 2.56k | related_work stringlengths 92 1.77k | ref_abstract sequence |
|---|---|---|---|---|
math9912167 | 1631980677 | Author(s): Kuperberg, Greg; Thurston, Dylan P. | Abstract: We give a purely topological definition of the perturbative quantum invariants of links and 3-manifolds associated with Chern-Simons field theory. Our definition is as close as possible to one given by Kontsevich. We will also establish some basic properties of these invariants, in particular that they are universally finite type with respect to algebraically split surgery and with respect to Torelli surgery. Torelli surgery is a mutual generalization of blink surgery of Garoufalidis and Levine and clasper surgery of Habiro. | Two other generalizations that can be considered are invariants of graphs in 3-manifolds, and invariants associated to other flat connections @cite_16 . We will analyze these in future work. Among other things, there should be a general relation between flat bundles and links in 3-manifolds on the one hand and finite covers and branched covers on the other hand @cite_26 . | {
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"This note is a sequel to our earlier paper of the same title [4] and describes invariants of rational homology 3-spheres associated to acyclic orthogonal local systems. Our work is in the spirit o... |
cs9910011 | 2168463568 | A statistical model for segmentation and word discovery in child directed speech is presented. An incremental unsupervised learning algorithm to infer word boundaries based on this model is described and results of empirical tests showing that the algorithm is competitive with other models that have been used for similar tasks are also presented. | Model Based Dynamic Programming, hereafter referred to as MBDP-1 @cite_0 , is probably the most recent work that addresses the exact same issue as that considered in this paper. Both the approach presented in this paper and Brent's MBDP-1 are based on explicit probability models. Approaches not based on explicit probability models include those based on information theoretic criteria such as MDL , transitional probability or simple recurrent networks . The maximum likelihood approach due to Olivier:SGL68 is probabilistic in the sense that it is geared towards explicitly calculating the most probable segmentation of each block of input utterances. However, it is not based on a formal statistical model. To avoid needless repetition, we only describe Brent's MBDP-1 below and direct the interested reader at Brent:EPS99 which provides an excellent review of many of the algorithms mentioned above. | {
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"This paper presents a model-based, unsupervised algorithm for recovering word boundaries in a natural-language text from which they have been deleted. The algorithm is derived from a probability model of the source that generated t... |
cs9911003 | 2950670108 | We solve the subgraph isomorphism problem in planar graphs in linear time, for any pattern of constant size. Our results are based on a technique of partitioning the planar graph into pieces of small tree-width, and applying dynamic programming within each piece. The same methods can be used to solve other planar graph problems including connectivity, diameter, girth, induced subgraph isomorphism, and shortest paths. | Recently we were able to characterize the graphs that can occur at most @math times as a subgraph isomorph in an @math -vertex planar graph: they are exactly the 3-connected planar graphs @cite_41 . However our proof does not lead to an efficient algorithm for 3-connected planar subgraph isomorphism. In this paper we use different techniques which do not depend on high-order connectivity. | {
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"It is well known that any planar graph contains at most O(n) complete subgraphs. We extend this to an exact characterization: G occurs O(n) times as a subgraph of any planar graph, if and only if G is three-connected. We generaliz... |
hep-th9908200 | 2160091034 | Daviau showed the equivalence of matrix Dirac theory, formulated within a spinor bundle (S_x C _x^4 ), to a Clifford algebraic formulation within space Clifford algebra (C ( R ^3 , ) M _ 2 ( C ) P ) Pauli algebra (matrices) ≃ ℍ ⨁ ℍ ≃ biquaternions. We will show, that Daviau's map θ: ( : C ^4 M _ 2 ( C ) ) is an isomorphism. It is shown that Hestenes' and Parra's formulations are equivalent to Daviau's Clifford algebra formulation, which uses outer automorphisms. The connection between different formulations is quite remarkable, since it connects the left and right action on the Pauli algebra itself viewed as a bi-module with the left (resp. right) action of the enveloping algebra (P^ P P^T on P ). The isomorphism established in this article and given by Daviau's map does clearly show that right and left actions are of similar type. This should be compared with attempts of Hestenes, Daviau, and others to interprete the right action as the iso-spin freedom. | A further genuine and important approach to the spinor-tensor transition was developed starting probably with Crawford by P. Lounesto, @cite_6 and references there. He investigated the question, how a spinor field can be reconstructed from known tensor densities. The major characterization is derived, using Fierz-Kofink identities, from elements called Boomerangs --because they are able to come back to the spinorial picture. Lounesto's result is a characterization of spinors based on multi-vector relations which unveils a new unknown type of spinor. | {
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"A historical review of spinors is given together with a construction of spinor spaces as minimal left ideals of Clifford algebras. Spinor spaces of euclidean spaces over reals have a natural linear structure over reals, complex num... |
cs9903014 | 1612660921 | We present an open architecture for just-in-time code generation and dynamic code optimization that is flexible, customizable, and extensible. While previous research has primarily investigated functional aspects of such a system, architectural aspects have so far remained unexplored. In this paper, we argue that these properties are important to generate optimal code for a variety of hardware architectures and different processor generations within processor families. These properties are also important to make system-level code generation useful in practice. | Pioneering research in dynamic runtime optimization was done by Hansen @cite_8 who first described a fully automated system for runtime code optimization. His system was similar in structure to our system---it was composed of a loader, a profiler, and an optimizer---but used profiling data only to decide when to optimize and what to optimize, not how to optimize. Also, his system interpreted code prior to optimization, since load time code generation was too memory and time consuming at the time. | {
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"Abstract : This thesis investigates adaptive compiler systems that perform, during program execution, code optimizations based on the dynamic behavior of the program as opposed to current approaches that employ a fixed code generat... |
cs9903014 | 1612660921 | We present an open architecture for just-in-time code generation and dynamic code optimization that is flexible, customizable, and extensible. While previous research has primarily investigated functional aspects of such a system, architectural aspects have so far remained unexplored. In this paper, we argue that these properties are important to generate optimal code for a variety of hardware architectures and different processor generations within processor families. These properties are also important to make system-level code generation useful in practice. | Hansen's work was followed by several other projects that have investigated the benefits of runtime optimization: the Smalltalk @cite_33 and SELF @cite_0 systems that focused on the benefits of dynamic optimization in an object-oriented environment; Morph'', a project developed at Harvard University @cite_16 ; and the system described by the authors of this paper @cite_4 @cite_30 . Other projects have experimented with optimization at link time rather than at runtime @cite_18 . At link time, many of the problems described in this paper are non-existent. Among them the decision when to optimize, what to optimize, and how to replace code. However, there is also a price to pay, namely that it cannot be performed in the presence of dynamic loading. | {
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"Despite the apparent success of the Java Virtual Machine, its ... |
cs9903014 | 1612660921 | We present an open architecture for just-in-time code generation and dynamic code optimization that is flexible, customizable, and extensible. While previous research has primarily investigated functional aspects of such a system, architectural aspects have so far remained unexplored. In this paper, we argue that these properties are important to generate optimal code for a variety of hardware architectures and different processor generations within processor families. These properties are also important to make system-level code generation useful in practice. | Common to the above-mentioned work is that the main focus has always been on functional aspects, that is how to profile and which optimizations to perform. Related to this is research on how to boost application performance by combining profiling data and code optimizations at compile time (not at runtime), including work on method dispatch optimizations for object-oriented programming languages @cite_22 @cite_35 , profile-guided intermodular optimizations @cite_3 @cite_26 , code positioning techniques @cite_13 @cite_25 , and profile-guided data cache locality optimizations @cite_29 @cite_10 @cite_12 . | {
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cs9903018 | 1593496962 | Scripting languages are becoming more and more important as a tool for software development, as they provide great flexibility for rapid prototyping and for configuring componentware applications. In this paper we present LuaJava, a scripting tool for Java. LuaJava adopts Lua, a dynamically typed interpreted language, as its script language. Great emphasis is given to the transparency of the integration between the two languages, so that objects from one language can be used inside the other like native objects. The final result of this integration is a tool that allows the construction of configurable Java applications, using off-the-shelf components, in a high abstraction level. | For Tcl @cite_13 two integration solutions exist: the TclBlend binding @cite_11 and the Jacl implementation @cite_14 . TclBlend is a binding between Java and Tcl, which, as LuaJava, allows Java objects to be manipulated by scripts. Some operations, such as access to fields and static method invocations, require specific functions. Calls to instance methods are handled naturally by Tcl commands. | {
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"This paper describes the motivations and strategies behind our group’s efforts to integrate the Tcl and Java programming languages. From the Java perspective, we w... |
hep-th9807171 | 1774239421 | The thesis begins with an introduction to M-theory (at a graduate student's level), starting from perturbative string theory and proceeding to dualities, D-branes and finally Matrix theory. The following chapter treats, in a self-contained way, of general classical p-brane solutions. Black and extremal branes are reviewed, along with their semi-classical thermodynamics. We then focus on intersecting extremal branes, the intersection rules being derived both with and without the explicit use of supersymmetry. The last three chapters comprise more advanced aspects of brane physics, such as the dynamics of open branes, the little theories on the world-volume of branes and how the four dimensional Schwarzschild black hole can be mapped to an extremal configuration of branes, thus allowing for a statistical interpretation of its entropy. The original results were already reported in hep-th 9701042, hep-th 9704190, hep-th 9710027 and hep-th 9801053. | The main objective of this chapter was to study the basic @math -branes that one encounters in M-theory, and to treat them in a unified way. The need to unify the treatment is inspired by U-duality @cite_22 @cite_86 @cite_144 , which states that from the effective lower dimensional space-time point of view, all the charges carried by the different branes are on the same footing. While string theory breaks' this U-duality symmetry, choosing the NSNS string to be the fundamental object of the perturbative theory, the supergravity low-energy effective theories realize the U-duality at the classical level. | {
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"Abstract The strong coupling dynamics of string theories in dimension d ⩾ 4 are studied. It is argued, among other things, that eleven-dimensional supergravity arises as a... |
hep-th9807171 | 1774239421 | The thesis begins with an introduction to M-theory (at a graduate student's level), starting from perturbative string theory and proceeding to dualities, D-branes and finally Matrix theory. The following chapter treats, in a self-contained way, of general classical p-brane solutions. Black and extremal branes are reviewed, along with their semi-classical thermodynamics. We then focus on intersecting extremal branes, the intersection rules being derived both with and without the explicit use of supersymmetry. The last three chapters comprise more advanced aspects of brane physics, such as the dynamics of open branes, the little theories on the world-volume of branes and how the four dimensional Schwarzschild black hole can be mapped to an extremal configuration of branes, thus allowing for a statistical interpretation of its entropy. The original results were already reported in hep-th 9701042, hep-th 9704190, hep-th 9710027 and hep-th 9801053. | It should also not be underestimated that the derivation of the intersecting solutions presented in this chapter is a thorough consistency check of all the dualities acting on, and between, the supergravity theories. It is straightforward to check that, starting from one definite configuration, all its dual configurations are also found between the solutions presented here (with the exception of the solutions involving waves and KK monopoles). In this line of thoughts, we presented a recipe for building five and four dimensional extreme supersymmetric black holes. Some of these black holes were used in the literature to perform a microscopic counting of their entropy, as in @cite_191 @cite_61 for the 5-dimensional ones. Actually, the only (5 dimensional) black holes in the U-duality orbit' that were counted were the ones containing only D-branes and KK momentum. It is still an open problem to directly count the microscopic states of the same black hole but in a different M-theoretic formulation. | {
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"Abstract The Bekenstein-Hawking area-entropy relation S BH = A 4 is derived for a class of five-dimensional extremal black holes in string theory by counting the degeneracy of BPS solition bound ... |
hep-th9807171 | 1774239421 | The thesis begins with an introduction to M-theory (at a graduate student's level), starting from perturbative string theory and proceeding to dualities, D-branes and finally Matrix theory. The following chapter treats, in a self-contained way, of general classical p-brane solutions. Black and extremal branes are reviewed, along with their semi-classical thermodynamics. We then focus on intersecting extremal branes, the intersection rules being derived both with and without the explicit use of supersymmetry. The last three chapters comprise more advanced aspects of brane physics, such as the dynamics of open branes, the little theories on the world-volume of branes and how the four dimensional Schwarzschild black hole can be mapped to an extremal configuration of branes, thus allowing for a statistical interpretation of its entropy. The original results were already reported in hep-th 9701042, hep-th 9704190, hep-th 9710027 and hep-th 9801053. | Some of the intersection rules intersectionrules point towards an M-theory interpretation in terms of open branes ending on other branes. This idea will be elaborated and made firmer in the next chapter. It suffices to say here that this interpretation is consistent with dualities if we postulate that the open character' of a fundamental string ending on a D-brane is invariant under dualities. S-duality directly implies, for instance, that D-strings can end on NS5-branes @cite_176 . Then T-dualities imply that all the D-branes can end on the NS5-brane. In particular, the fact that the D2-brane can end on the NS5-brane should imply that the M5-brane is a D-brane for the M2-branes @cite_176 @cite_143 @cite_38 (this could also be extrapolated from the fact that a F1-string ends on a D4-brane). In the next chapter we will see how these ideas are further supported by the presence of the Chern-Simons terms in the supergravities, and by the structure of the world-volume effective actions of the branes. | {
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"Abstract Various aspects of branes in the recently proposed matrix model for M-theory are discussed. A careful analysis of the supersymmetry algebra of the matrix model u... |
hep-th9807171 | 1774239421 | The thesis begins with an introduction to M-theory (at a graduate student's level), starting from perturbative string theory and proceeding to dualities, D-branes and finally Matrix theory. The following chapter treats, in a self-contained way, of general classical p-brane solutions. Black and extremal branes are reviewed, along with their semi-classical thermodynamics. We then focus on intersecting extremal branes, the intersection rules being derived both with and without the explicit use of supersymmetry. The last three chapters comprise more advanced aspects of brane physics, such as the dynamics of open branes, the little theories on the world-volume of branes and how the four dimensional Schwarzschild black hole can be mapped to an extremal configuration of branes, thus allowing for a statistical interpretation of its entropy. The original results were already reported in hep-th 9701042, hep-th 9704190, hep-th 9710027 and hep-th 9801053. | In this chapter we presented only extremal configurations of intersecting branes. The natural further step to take would be to consider also non-extremal configurations of intersecting branes. There is however a subtlety: there could be a difference between intersections of non-extremal branes, and non-extremal intersections of otherwise extremal branes. If we focus on bound states (and thus not on configurations of well separated branes), it appears that a non-extremal configuration would be characterized for instance by @math charges and by its mass. There is only one additional parameter with respect to the extremal configurations. Physically, we could have hardly expected to have, say, as many non-extremality parameters as the number of branes in the bound state. Indeed, non-extremality can be roughly associated to the branes being in an excited state, and it would have thus been very unlikely that the excitations did not mix between the various branes in the bound state. Non-extremal intersecting brane solutions were found first in @cite_48 , and were derived from the equations of motion following a similar approach as here in @cite_81 @cite_16 . | {
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"Abstract We present non-extreme generalisations of intersecting p -brane solutions of eleven-dimensional supergravity which upon toroidal compactification reduce to non-ext... |
hep-th9807171 | 1774239421 | The thesis begins with an introduction to M-theory (at a graduate student's level), starting from perturbative string theory and proceeding to dualities, D-branes and finally Matrix theory. The following chapter treats, in a self-contained way, of general classical p-brane solutions. Black and extremal branes are reviewed, along with their semi-classical thermodynamics. We then focus on intersecting extremal branes, the intersection rules being derived both with and without the explicit use of supersymmetry. The last three chapters comprise more advanced aspects of brane physics, such as the dynamics of open branes, the little theories on the world-volume of branes and how the four dimensional Schwarzschild black hole can be mapped to an extremal configuration of branes, thus allowing for a statistical interpretation of its entropy. The original results were already reported in hep-th 9701042, hep-th 9704190, hep-th 9710027 and hep-th 9801053. | Supergravity solutions corresponding to D-branes at angles were found in @cite_31 @cite_59 @cite_178 . The resulting solutions contain as expected off-diagonal elements in the internal metric, and the derivation from the equations of motion as in @cite_59 is accordingly rather intricated. | {
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"A low-energy background field solution is presented which describes several D-membranes oriented at angles with respect to one another. The mass and charge densities for t... |
hep-th9807171 | 1774239421 | The thesis begins with an introduction to M-theory (at a graduate student's level), starting from perturbative string theory and proceeding to dualities, D-branes and finally Matrix theory. The following chapter treats, in a self-contained way, of general classical p-brane solutions. Black and extremal branes are reviewed, along with their semi-classical thermodynamics. We then focus on intersecting extremal branes, the intersection rules being derived both with and without the explicit use of supersymmetry. The last three chapters comprise more advanced aspects of brane physics, such as the dynamics of open branes, the little theories on the world-volume of branes and how the four dimensional Schwarzschild black hole can be mapped to an extremal configuration of branes, thus allowing for a statistical interpretation of its entropy. The original results were already reported in hep-th 9701042, hep-th 9704190, hep-th 9710027 and hep-th 9801053. | Other half-supersymmetric bound states of this class are the @math multiplets of 1- and 5-branes in type IIB theory @cite_95 @cite_0 , or more precisely the configurations F1 @math D1 and NS5 @math D5, also called @math 1- and 5-branes, where @math is the NSNS charge and @math the RR charge of the compound. The classical solutions corresponding to this latter case were actually found more simply performing an @math transformation on the F1 or NS5 solutions. | {
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"The recent discovery of an explicit conformal field theory description of Type II p-branes makes it possible to investigate the existence of bound states of such objects. In particular, it is possi... |
hep-th9807171 | 1774239421 | The thesis begins with an introduction to M-theory (at a graduate student's level), starting from perturbative string theory and proceeding to dualities, D-branes and finally Matrix theory. The following chapter treats, in a self-contained way, of general classical p-brane solutions. Black and extremal branes are reviewed, along with their semi-classical thermodynamics. We then focus on intersecting extremal branes, the intersection rules being derived both with and without the explicit use of supersymmetry. The last three chapters comprise more advanced aspects of brane physics, such as the dynamics of open branes, the little theories on the world-volume of branes and how the four dimensional Schwarzschild black hole can be mapped to an extremal configuration of branes, thus allowing for a statistical interpretation of its entropy. The original results were already reported in hep-th 9701042, hep-th 9704190, hep-th 9710027 and hep-th 9801053. | In @cite_106 (inspired by @cite_54 ) a solution is presented which corresponds to a M5 @math M5=1 configuration, which follows the harmonic superposition rule, provided however that the harmonic functions depend on the respective relative transverse space (i.e. they are functions of two different spaces). The problem now is that the harmonic functions do not depend on the overall transverse space (which is 1-dimensional in the case above), the configuration thus not being localized there. A method actually inspired by the one presented here to derive the intersecting brane solutions, has been applied in @cite_89 to the intersections of this second kind. Imposing that the functions depend on the relative transverse space(s) (with factorized dependence) and not on the overall one, the authors of @cite_89 arrive at a formula for the intersections very similar to intersectionrules , with @math on the l.h.s. This rule correctly reproduces the M5 @math M5=1 configuration, and moreover also all the configurations of two D-branes with 8 Neumann-Dirichlet directions, which preserve @math supersymmetries but were excluded from the intersecting solutions derived in this chapter (only the configurations with 4 ND directions were found as solutions). One such configuration is e.g. D0 @math D8. | {
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"We derive an exact stringlike soliton solution of [ital D]=10 heterotic string theory. The solution possesses SU(2)[times]SU(2) instanton structure in the eight-dimensiona... |
1903.05435 | 2921710190 | In this work, we are interested in the applications of big data in the telecommunication domain, analysing two weeks of datasets provided by Telecom Italia for Milan and Trento. Our objective is to identify hotspots which are places with very high communication traffic relative to others and measure the interaction between them. We model the hotspots as nodes in a graph and then apply node centrality metrics that quantify the importance of each node. We review five node centrality metrics and show that they can be divided into two families: the first family is composed of closeness and betweenness centrality whereas the second family consists of degree, PageRank and eigenvector centrality. We then proceed with a statistical analysis in order to evaluate the consistency of the results over the two weeks. We find out that the ranking of the hotspots under the various centrality metrics remains practically the same with the time for both Milan and Trento. We further identify that the relative difference of the values of the metrics is smaller for PageRank centrality than for closeness centrality and this holds for both Milan and Trento. Finally, our analysis reveals that the variance of the results is significantly smaller for Trento than for Milan. | Nowadays, telecom companies use widely big data in order to mine the behaviour of their customers, improve the quality of service that they provide and reduce the customers' churn. Towards this direction, demographic statistics, network deployments and call detail records (CDRs) are key factors that need to be carefully integrated in order to make accurate predictions. Though there are various open source data for the first two factors, researchers rarely have access to traffic demand data, since it is a sensitive information for the operators. Therefore, researchers need to rely on synthetic models, which do not always capture accurately large-scale mobile networks @cite_5 . | {
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"In a world of open data and large-scale measurements, it is often feasible to obtain a real-world trace to fit to one's research problem. Feasible, however, does not imply simple. Taking next-generation cellular network planning as... |
1903.05435 | 2921710190 | In this work, we are interested in the applications of big data in the telecommunication domain, analysing two weeks of datasets provided by Telecom Italia for Milan and Trento. Our objective is to identify hotspots which are places with very high communication traffic relative to others and measure the interaction between them. We model the hotspots as nodes in a graph and then apply node centrality metrics that quantify the importance of each node. We review five node centrality metrics and show that they can be divided into two families: the first family is composed of closeness and betweenness centrality whereas the second family consists of degree, PageRank and eigenvector centrality. We then proceed with a statistical analysis in order to evaluate the consistency of the results over the two weeks. We find out that the ranking of the hotspots under the various centrality metrics remains practically the same with the time for both Milan and Trento. We further identify that the relative difference of the values of the metrics is smaller for PageRank centrality than for closeness centrality and this holds for both Milan and Trento. Finally, our analysis reveals that the variance of the results is significantly smaller for Trento than for Milan. | For example, the authors in @cite_4 analyse an heterogeneous cellular network which consists of different types of nodes, such as macrocells and microcells. Nowadays a popular model is the one from Wyner @cite_0 , but it fails to fully capture a real heterogeneous cellular network because it is simplistic. Another approach is to use the spatial Poisson point process model (SPPP) @cite_9 , which can be derived from the premise that all base stations are uniformly distributed. However, a city can be classified in different areas, which have different population densities. These different areas can be characterised as dense urban, urban and suburban. To be able to classify the heterogeneous networks into these areas, the authors introduce SPPP for homogeneous and inhomogeneous sets. They show that the SPPP-model captures accurately both urban and suburban areas, whereas this is not the case for dense urban areas, because of a considerable population concentrated in small areas. | {
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"The Wyner model has been widely used to model and analyze cellular networks due to its simplicity and analytical tractability. Its key aspects include fixed user locations and... |
1903.05355 | 2968491849 | Learning the dynamics of robots from data can help achieve more accurate tracking controllers, or aid their navigation algorithms. However, when the actual dynamics of the robots change due to external conditions, on-line adaptation of their models is required to maintain high fidelity performance. In this work, a framework for on-line learning of robot dynamics is developed to adapt to such changes. The proposed framework employs an incremental support vector regression method to learn the model sequentially from data streams. In combination with the incremental learning, strategies for including and forgetting data are developed to obtain better generalization over the whole state space. The framework is tested in simulation and real experimental scenarios demonstrating its adaptation capabilities to changes in the robot’s dynamics. | In the field of marine robotics, @cite_10 used locally weighted projection regression to compensate the mismatch between the physics based model and the sensors reading of the AUV Nessie. Auto-regressive networks augmented with a genetic algorithm as a gating network were used to identify the model of a simulated AUV with variable mass. In a previous work @cite_16 , an on-line adaptation method was proposed to model the change in the damping forces resulting from a structural change of an AUVs mechanical structure. The algorithm showed good adaptation capability but was only limited to modelling the damping effect of an AUV model. In this work we build upon our the results of @cite_14 @cite_11 to provide a general framework for on-line learning of AUV fully coupled nonlinear dynamics, and validating the proposed approach on simulated data as well as real robot data. | {
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"abstract": [
"This work addresses a data driven approach which employs a machine learning technique known as Support Vector Regression (SVR), to identif... |
1903.05454 | 2950587559 | In this work, we present a camera geopositioning system based on matching a query image against a database with panoramic images. For matching, our system uses memory vectors aggregated from global image descriptors based on convolutional features to facilitate fast searching in the database. To speed up searching, a clustering algorithm is used to balance geographical positioning and computation time. We refine the obtained position from the query image using a new outlier removal algorithm. The matching of the query image is obtained with a recall@5 larger than 90 for panorama-to-panorama matching. We cluster available panoramas from geographically adjacent locations into a single compact representation and observe computational gains of approximately 50 at the cost of only a small (approximately 3 ) recall loss. Finally, we present a coordinate estimation algorithm that reduces the median geopositioning error by up to 20 . | In recent years, research regarding image matching has been influenced by the developments in other areas of computer vision. Deep learning architectures have been developed both for image matching @cite_10 @cite_1 @cite_17 and geopositioning @cite_13 @cite_5 @cite_18 with attractive results. | {
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1903.05454 | 2950587559 | In this work, we present a camera geopositioning system based on matching a query image against a database with panoramic images. For matching, our system uses memory vectors aggregated from global image descriptors based on convolutional features to facilitate fast searching in the database. To speed up searching, a clustering algorithm is used to balance geographical positioning and computation time. We refine the obtained position from the query image using a new outlier removal algorithm. The matching of the query image is obtained with a recall@5 larger than 90 for panorama-to-panorama matching. We cluster available panoramas from geographically adjacent locations into a single compact representation and observe computational gains of approximately 50 at the cost of only a small (approximately 3 ) recall loss. Finally, we present a coordinate estimation algorithm that reduces the median geopositioning error by up to 20 . | Convolutional features extracted from the deep layers of CNNs have shown great utility when addressing image matching and retrieval problems. Babenko @cite_10 employ pre-trained networks to generate descriptors based on high-level convolutional features used for retrieving images of various landmarks. Sunderhauf @cite_2 solve the problem of urban scene recognition, employing salient regions and convolutional features of local objects. This method is extended in @cite_8 , where additional spatial information is used to increase the algorithm performance. | {
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1903.05454 | 2950587559 | In this work, we present a camera geopositioning system based on matching a query image against a database with panoramic images. For matching, our system uses memory vectors aggregated from global image descriptors based on convolutional features to facilitate fast searching in the database. To speed up searching, a clustering algorithm is used to balance geographical positioning and computation time. We refine the obtained position from the query image using a new outlier removal algorithm. The matching of the query image is obtained with a recall@5 larger than 90 for panorama-to-panorama matching. We cluster available panoramas from geographically adjacent locations into a single compact representation and observe computational gains of approximately 50 at the cost of only a small (approximately 3 ) recall loss. Finally, we present a coordinate estimation algorithm that reduces the median geopositioning error by up to 20 . | The problem of geopositioning can be seen as a dedicated branch of image retrieval. In this case, the objective is to compute extrinsic parameters (or coordinates) of a camera capturing the query image, based on the matched georeferenced images from a database. There exist many different algorithms and neural network architectures that attempt to identify the geographical location of a street-level query image. Lin @cite_13 learn deep representations for matching aerial and ground images. Workman @cite_18 use spatial features at multiple scales which are fused with street-level features, to solve the problem of geolocalization. @cite_5 , a fully automated processing pipeline matches multi-view stereo (MVS) models to aerial images. This matching algorithm handles the viewpoint variance across aerial and street-level images. | {
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1903.05454 | 2950587559 | In this work, we present a camera geopositioning system based on matching a query image against a database with panoramic images. For matching, our system uses memory vectors aggregated from global image descriptors based on convolutional features to facilitate fast searching in the database. To speed up searching, a clustering algorithm is used to balance geographical positioning and computation time. We refine the obtained position from the query image using a new outlier removal algorithm. The matching of the query image is obtained with a recall@5 larger than 90 for panorama-to-panorama matching. We cluster available panoramas from geographically adjacent locations into a single compact representation and observe computational gains of approximately 50 at the cost of only a small (approximately 3 ) recall loss. Finally, we present a coordinate estimation algorithm that reduces the median geopositioning error by up to 20 . | A common factor of the above work is that it either requires the combination of aerial and street-level images for geopositioning, or extensive training on specific datasets. Both cases and their solutions cannot be easily generalized. In our approach, we utilize georeferenced, street-level panoramic images only and a pre-trained CNN combined with image matching techniques for coordinate estimation. This avoids lengthy training and labeling procedures and assumes street-level data to be available without requiring aerial images. Furthermore, and unlike @cite_1 , we do not assume that our query and database images originate from the same imaging devices. | {
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"Location recognition is commonly treated as visual instance retrieval on \"street view\" imagery. The dataset items and queries are panoramic views, i.e. groups of images taken at a single location. This work introduces a novel pan... |
1903.05524 | 2972959293 | In this paper, we study the relationship between two crucial properties in linear dynamical networks of diffusively coupled agents, that is controllability and robustness to noise and structural changes in the network. In particular, for any given network size and diameter, we identify networks that are maximally robust and then analyze their strong structural controllability. We do so by determining the minimum number of leaders to make such networks completely controllable with arbitrary coupling weights between agents. Similarly, we design networks with the same given parameters that are completely controllable independent of coupling weights through a minimum number of leaders, and then also analyze their robustness. We utilize the notion of Kirchhoff index to measure network robustness to noise and structural changes. Our controllability analysis is based on novel graph-theoretic methods that offer insights on the important connection between network robustness and strong structural controllability in such networks. | Kirchhoff index or equivalently effective graph resistance based measures have been instrumental in quantifying the effect of noise on the expected steady state dispersion in linear dynamical networks, particularly in the ones with the consensus dynamics, for instance see @cite_23 @cite_8 @cite_22 . Furthermore, limits on robustness measures that quantify expected steady-state dispersion due to external stochastic disturbances in linear dynamical networks are also studied in @cite_9 @cite_10 . To maximize robustness in networks by minimizing their Kirchhoff indices, various optimization approaches (e.g., @cite_26 @cite_1 ) including graph-theoretic ones @cite_0 have been proposed. The main objective there is to determine crucial edges that need to be added or maintained to maximize robustness under given constraints @cite_11 . | {
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1903.05524 | 2972959293 | In this paper, we study the relationship between two crucial properties in linear dynamical networks of diffusively coupled agents, that is controllability and robustness to noise and structural changes in the network. In particular, for any given network size and diameter, we identify networks that are maximally robust and then analyze their strong structural controllability. We do so by determining the minimum number of leaders to make such networks completely controllable with arbitrary coupling weights between agents. Similarly, we design networks with the same given parameters that are completely controllable independent of coupling weights through a minimum number of leaders, and then also analyze their robustness. We utilize the notion of Kirchhoff index to measure network robustness to noise and structural changes. Our controllability analysis is based on novel graph-theoretic methods that offer insights on the important connection between network robustness and strong structural controllability in such networks. | To quantify controllability, several approaches have been adapted, including determining the minimum number of inputs (leader nodes) needed to (structurally or strong structurally) control a network, determining the worst-case control energy, metrics based on controllability Gramians, and so on (e.g., see @cite_7 @cite_5 ). Strong structural controllability, due to its independence on coupling weights between nodes, is a generalized notion of controllability with practical implications. There have been recent studies providing graph-theoretic characterizations of this concept @cite_20 @cite_13 @cite_17 . There are numerous other studies regarding leader selection to optimize network performance measures under various constraints, such as to minimize the deviation from consensus in a noisy environment @cite_4 @cite_2 , and to maximize various controllability measures, for instance @cite_15 @cite_18 @cite_25 @cite_14 . Recently, optimization methods are also presented to select leader nodes that exploit submodularity properties of performance measures for network robustness and structural controllability @cite_5 @cite_3 . | {
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1903.05524 | 2972959293 | In this paper, we study the relationship between two crucial properties in linear dynamical networks of diffusively coupled agents, that is controllability and robustness to noise and structural changes in the network. In particular, for any given network size and diameter, we identify networks that are maximally robust and then analyze their strong structural controllability. We do so by determining the minimum number of leaders to make such networks completely controllable with arbitrary coupling weights between agents. Similarly, we design networks with the same given parameters that are completely controllable independent of coupling weights through a minimum number of leaders, and then also analyze their robustness. We utilize the notion of Kirchhoff index to measure network robustness to noise and structural changes. Our controllability analysis is based on novel graph-theoretic methods that offer insights on the important connection between network robustness and strong structural controllability in such networks. | Very recently in @cite_21 , trade-off between controllability and fragility in complex networks is investigated. Fragility measures the smallest perturbation in edge weights to make the network unstable. Authors in @cite_21 show that networks that require small control energy, as measured by the eigen values of the controllability Gramian, to drive from one state to another are more fragile and vice versa. In our work, for control performance, we consider minimum leaders for strong structural controllability, which is independent of coupling weights; and for robustness, we utilize the Kirchhoff index which measures robustness to noise as well as to structural changes in the underlying network graph. Moreover, in this work we focus on designing and comparing extremal networks for these properties. The rest of the paper is organized as follows: Section describes preliminaries and network dynamics. Section explains the measures for robustness and controllability, and also outlines the main problems. Section presents maximally robust networks for a given @math and @math , and also analyzes their controllability. Section provides a design of maximally controllable networks and also evaluates their robustness. Finally, Section concludes the paper. | {
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"Mathematical theories and empirical evidence suggest that several complex natural and man-made systems are fragile: as their size increases, arbitrarily small and localized alterations of the system parameters may trigger system-w... |
cmp-lg9408015 | 2952406681 | Effective problem solving among multiple agents requires a better understanding of the role of communication in collaboration. In this paper we show that there are communicative strategies that greatly improve the performance of resource-bounded agents, but that these strategies are highly sensitive to the task requirements, situation parameters and agents' resource limitations. We base our argument on two sources of evidence: (1) an analysis of a corpus of 55 problem solving dialogues, and (2) experimental simulations of collaborative problem solving dialogues in an experimental world, Design-World, where we parameterize task requirements, agents' resources and communicative strategies. | Design-World is also based on the method used in Carletta's JAM simulation for the Edinburgh Map-Task @cite_10 . JAM is based on the Map-Task Dialogue corpus, where the goal of the task is for the planning agent, the instructor, to instruct the reactive agent, the instructee, how to get from one place to another on the map. JAM focuses on efficient strategies for recovery from error and parametrizes agents according to their communicative and error recovery strategies. Given good error recovery strategies, Carletta argues that high risk' strategies are more efficient, where efficiency is a measure of the number of utterances in the dialogue. While the focus here is different, we have shown that that the number of utterances is just one parameter for evaluating performance, and that the task definition determines when strategies are effective. | {
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"The Principle of Parsimony states that people usually try to complete tasks with the least effort that will produce a satisfactory solution. In task-oriented dialogue, this produces a tension between conveying information carefull... |
cs9907027 | 2949190809 | The aim of the Alma project is the design of a strongly typed constraint programming language that combines the advantages of logic and imperative programming. The first stage of the project was the design and implementation of Alma-0, a small programming language that provides a support for declarative programming within the imperative programming framework. It is obtained by extending a subset of Modula-2 by a small number of features inspired by the logic programming paradigm. In this paper we discuss the rationale for the design of Alma-0, the benefits of the resulting hybrid programming framework, and the current work on adding constraint processing capabilities to the language. In particular, we discuss the role of the logical and customary variables, the interaction between the constraint store and the program, and the need for lists. | We concentrate here on the related work involving addition of constraints to imperative languages. For an overview of related work pertaining to the language we refer the reader to @cite_0 . | {
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"We describe here an implemented small programming language, called Alma-O, that augments the expressive power of imperative programming by a limited number of features inspired by the logic programming paradigm. These additions enc... |
cmp-lg9709007 | 1578881253 | Automatic Text Categorization (TC) is a complex and useful task for many natural language applications, and is usually performed through the use of a set of manually classified documents, a training collection. We suggest the utilization of additional resources like lexical databases to increase the amount of information that TC systems make use of, and thus, to improve their performance. Our approach integrates WordNet information with two training approaches through the Vector Space Model. The training approaches we test are the Rocchio (relevance feedback) and the Widrow-Hoff (machine learning) algorithms. Results obtained from evaluation show that the integration of WordNet clearly outperforms training approaches, and that an integrated technique can effectively address the classification of low frequency categories. | To our knowledge, lexical databases have been used only once before in TC, apart from our previous work. Hearst @cite_10 adapted a disambiguation algorithm by Yarowsky using WordNet to recognize category occurrences. Categories are made of WordNet terms, which is not the general case of standard or user-defined categories. It is a hard task to adapt WordNet subsets to pre-existing categories, especially when they are domain dependent. Hearst's approach has shown promising results confirmed by our previous work @cite_23 and present results. | {
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cmp-lg9709007 | 1578881253 | Automatic Text Categorization (TC) is a complex and useful task for many natural language applications, and is usually performed through the use of a set of manually classified documents, a training collection. We suggest the utilization of additional resources like lexical databases to increase the amount of information that TC systems make use of, and thus, to improve their performance. Our approach integrates WordNet information with two training approaches through the Vector Space Model. The training approaches we test are the Rocchio (relevance feedback) and the Widrow-Hoff (machine learning) algorithms. Results obtained from evaluation show that the integration of WordNet clearly outperforms training approaches, and that an integrated technique can effectively address the classification of low frequency categories. | Lexical databases have been employed recently in word sense disambiguation. For example, Agirre and Rigau @cite_4 make use of a semantic distance that takes into account structural factors in WordNet for achieving good results for this task. Additionally, Resnik @cite_3 combines the use of WordNet and a text collection for a definition of a distance for disambiguating noun groupings. Although the text collection is not a training collection (in the sense of a collection of manually labeled texts for a pre-defined text processing task), his approach can be regarded as the most similar to ours in the disambiguation setting. Finally, Ng and Lee @cite_11 make use of several sources of information inside a training collection (neighborhood, part of speech, morphological form, etc.) to get good results in disambiguating unrestricted text. | {
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cmp-lg9706006 | 2953123431 | Learning problems in the text processing domain often map the text to a space whose dimensions are the measured features of the text, e.g., its words. Three characteristic properties of this domain are (a) very high dimensionality, (b) both the learned concepts and the instances reside very sparsely in the feature space, and (c) a high variation in the number of active features in an instance. In this work we study three mistake-driven learning algorithms for a typical task of this nature -- text categorization. We argue that these algorithms -- which categorize documents by learning a linear separator in the feature space -- have a few properties that make them ideal for this domain. We then show that a quantum leap in performance is achieved when we further modify the algorithms to better address some of the specific characteristics of the domain. In particular, we demonstrate (1) how variation in document length can be tolerated by either normalizing feature weights or by using negative weights, (2) the positive effect of applying a threshold range in training, (3) alternatives in considering feature frequency, and (4) the benefits of discarding features while training. Overall, we present an algorithm, a variation of Littlestone's Winnow, which performs significantly better than any other algorithm tested on this task using a similar feature set. | The methods that are most similar to our techniques are the on-line algorithms used in @cite_16 and @cite_10 . In the first, two algorithms, a multiplicative update and additive update algorithms suggested in @cite_5 are evaluated in the domain, and are shown to perform somewhat better than Rocchio's algorithm. While both these works make use of multiplicative update algorithms, as we do, there are two major differences between those studies and the current one. First, there are some important technical differences between the algorithms used. Second, the algorithms we study here are mistake-driven; they update the weight vector only when a mistake is made, and not after every example seen. The Experts algorithm studied in @cite_10 is very similar to a basic version of the algorithm which we study here. The way we treat the negative weights is different, though, and significantly more efficient, especially in sparse domains (see ). Cohen and Singer experiment also, using the same algorithm, with more complex features (sparse n-grams) and show that, as expected, it yields better results. | {
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cmp-lg9701003 | 2952751702 | In expert-consultation dialogues, it is inevitable that an agent will at times have insufficient information to determine whether to accept or reject a proposal by the other agent. This results in the need for the agent to initiate an information-sharing subdialogue to form a set of shared beliefs within which the agents can effectively re-evaluate the proposal. This paper presents a computational strategy for initiating such information-sharing subdialogues to resolve the system's uncertainty regarding the acceptance of a user proposal. Our model determines when information-sharing should be pursued, selects a focus of information-sharing among multiple uncertain beliefs, chooses the most effective information-sharing strategy, and utilizes the newly obtained information to re-evaluate the user proposal. Furthermore, our model is capable of handling embedded information-sharing subdialogues. | Grosz, Sidner and Lochbaum @cite_7 @cite_1 developed a SharedPlan approach to modelling collaborative discourse, and Sidner formulated an artificial language for modeling such discourse. Sidner viewed a collaborative planning process as proposal acceptance and proposal rejection sequences. Her artificial language treats an utterance such as Why do X? as a proposal for the hearer to provide support for his proposal to do X. However, Sidner's work is descriptive and does not provide a mechanism for determining when and how such a proposal should be made nor how responses should be formulated in information-sharing subdialogues. | {
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cmp-lg9701003 | 2952751702 | In expert-consultation dialogues, it is inevitable that an agent will at times have insufficient information to determine whether to accept or reject a proposal by the other agent. This results in the need for the agent to initiate an information-sharing subdialogue to form a set of shared beliefs within which the agents can effectively re-evaluate the proposal. This paper presents a computational strategy for initiating such information-sharing subdialogues to resolve the system's uncertainty regarding the acceptance of a user proposal. Our model determines when information-sharing should be pursued, selects a focus of information-sharing among multiple uncertain beliefs, chooses the most effective information-sharing strategy, and utilizes the newly obtained information to re-evaluate the user proposal. Furthermore, our model is capable of handling embedded information-sharing subdialogues. | Several researchers have studied the role of clarification dialogues in disambiguating user plans @cite_3 @cite_5 and in understanding referring expressions @cite_8 . developed an automated librarian that could revise its beliefs and intentions and could generate responses as an attempt to revise the user's beliefs and intentions. Although their system had rules for asking the user whether he holds a particular belief and for telling the system's attitude toward a belief, the emphasis of their work was on conflict resolution and plan disambiguation. Thus they did not investigate a comprehensive strategy for information-sharing during proposal evaluation. For example, they did not identify situations in which information-sharing is necessary, did not address how to select a focus of information-sharing when there are multiple uncertain beliefs, did not consider requesting the user's justifications for a belief, etc. In addition, they do not provide an overall dialogue planner that takes into account discourse structure and appropriately captures embedded subdialogues. | {
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cmp-lg9606025 | 2952364737 | This paper presents an analysis conducted on a corpus of software instructions in French in order to establish whether task structure elements (the procedural representation of the users' tasks) are alone sufficient to control the grammatical resources of a text generator. We show that the construct of genre provides a useful additional source of control enabling us to resolve undetermined cases. | The results from our linguistic analysis are consistent with other research on sublanguages in the instructions domain, in both French and English, e.g., @cite_5 @cite_4 . Our analysis goes beyond previous work by identifying within the discourse context the means for exercising explicit control over a text generator. | {
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cmp-lg9505006 | 1617827527 | In previous work we studied a new type of DCGs, Datalog grammars, which are inspired on database theory. Their efficiency was shown to be better than that of their DCG counterparts under (terminating) OLDT-resolution. In this article we motivate a variant of Datalog grammars which allows us a meta-grammatical treatment of coordination. This treatment improves in some respects over previous work on coordination in logic grammars, although more research is needed for testing it in other respects. | A notion that is central to recent work on ellipsis, and which has been present in embryonic form, as we have seen, even in the early work on coordination, is that of parallelism as a key element in the determination of implicit meanings. Asher @cite_3 defines parallelism as | {
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cmp-lg9505006 | 1617827527 | In previous work we studied a new type of DCGs, Datalog grammars, which are inspired on database theory. Their efficiency was shown to be better than that of their DCG counterparts under (terminating) OLDT-resolution. In this article we motivate a variant of Datalog grammars which allows us a meta-grammatical treatment of coordination. This treatment improves in some respects over previous work on coordination in logic grammars, although more research is needed for testing it in other respects. | a) neither method formulates exactly how parallelism is to be determined- it is just postulated as a prerequisite to the resolution of ellipsis (although @cite_6 speculates on possible ways of formulating this, leaving it for future work) | {
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cmp-lg9505006 | 1617827527 | In previous work we studied a new type of DCGs, Datalog grammars, which are inspired on database theory. Their efficiency was shown to be better than that of their DCG counterparts under (terminating) OLDT-resolution. In this article we motivate a variant of Datalog grammars which allows us a meta-grammatical treatment of coordination. This treatment improves in some respects over previous work on coordination in logic grammars, although more research is needed for testing it in other respects. | By examining ellipsis in the context of coordinated structures, which are parallel by definition, and by using extended DLGs, we provide a method in which parallel structures are detected and resolved through syntactic and semantic criteria, and which can be applied to either grammars using different semantic representations- feature structure, @math -calculus, or other. We exemplify using a logic based semantics along the lines of @cite_8 . | {
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cmp-lg9505038 | 2952182676 | Augmented reality is a research area that tries to embody an electronic information space within the real world, through computational devices. A crucial issue within this area, is the recognition of real world objects or situations. In natural language processing, it is much easier to determine interpretations of utterances, even if they are ill-formed, when the context or situation is fixed. We therefore introduce robust, natural language processing into a system of augmented reality with situation awareness. Based on this idea, we have developed a portable system, called the Ubiquitous Talker. This consists of an LCD display that reflects the scene at which a user is looking as if it is a transparent glass, a CCD camera for recognizing real world objects with color-bar ID codes, a microphone for recognizing a human voice and a speaker which outputs a synthesized voice. The Ubiquitous Talker provides its user with some information related to a recognized object, by using the display and voice. It also accepts requests or questions as voice inputs. The user feels as if he she is talking with the object itself through the system. | Ubiquitous computing @cite_4 proposes that very small computational devices (i.e., ubiquitous computers) be embedded and integrated into physical environments in such a way that they operate seamlessly and almost transparently. These devices are aware of their physical surroundings. In contrast to ubiquitous computers, our barcode (color-code) system is a low cost and reliable solution to making everything a computer. Suppose that every page in a book has a unique barcode. When the user opens a page, its page ID is detected by the system, so it can supply specific information regarding the page. When the user adds some information to the page, the system stores it with the page ID tagged for later retrieval. This is almost the same as having a computer in every page of the book without the cost. Our ID-aware system is better than ubiquitous computers from the viewpoint of reliability and cost-performance, since it does not require batteries and never breaks down. | {
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"abstract": [
"Ubiquitous computing is the method of enhancing computer use by making many computers available throughout the physical environment, but making them effectively invisible to the user. Since we started this work at Xerox PARC in 198... |
math9702221 | 2117609843 | This paper reexamines univariate reduction from a toric geometric point of view. We begin by constructing a binomial variant of the @math -resultant and then retailor the generalized characteristic polynomial to fully exploit sparsity in the monomial structure of any given polynomial system. We thus obtain a fast new algorithm for univariate reduction and a better understanding of the underlying projections. As a corollary, we show that a refinement of Hilbert's Tenth Problem is decidable within single-exponential time. We also show how certain multisymmetric functions of the roots of polynomial systems can be calculated with sparse resultants. | From an applied angle, our observations on degeneracies and handling polynomial systems with infinitely many roots nicely complement the work of Emiris and Canny @cite_43 . In particular, their sparse resultant based algorithms for polynomial system solving can now be made to work even when problem B occurs. Also, an added benefit of working torically (as opposed to the classical approach of working in projective space) is the increased efficiency of the sparse resultant: the resulting matrix calculations (for polynomial system solving) are much smaller and faster. In particular, whereas it was remarked in @cite_41 that Gr "obner basis methods are likely to be faster than the GCP for sparse polynomial systems, the toric GCP appears to be far more competitive in such a comparison. | {
"cite_N": [
"@cite_41",
"@cite_43"
],
"mid": [
"1976392590",
"2066130115"
],
"abstract": [
"Multipolynomial resultants provide the most efficient methods known (in terms as asymptoticcomplexity) for solving certain systems of polynomial equations or eliminating variables (, 1988). The re... |
cmp-lg9503009 | 2951769629 | This paper presents an algorithm for tagging words whose part-of-speech properties are unknown. Unlike previous work, the algorithm categorizes word tokens in context instead of word types. The algorithm is evaluated on the Brown Corpus. | The simplest part-of-speech taggers are bigram or trigram models @cite_12 @cite_1 . They require a relatively large tagged training text. Transformation-based tagging as introduced by also requires a hand-tagged text for training. No pretagged text is necessary for Hidden Markov Models @cite_7 @cite_13 @cite_2 . Still, a lexicon is needed that specifies the possible parts of speech for every word. have shown that the effort necessary to construct the part-of-speech lexicon can be considerably reduced by combining learning procedures and a partial part-of-speech categorization elicited from an informant. | {
"cite_N": [
"@cite_7",
"@cite_1",
"@cite_2",
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],
"mid": [
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"",
"2046224275",
"1509596266"
],
"abstract": [
"Abstract A system for part-of-speech tagging is described. It is based on a hidden Markov model which can b... |
cmp-lg9503009 | 2951769629 | This paper presents an algorithm for tagging words whose part-of-speech properties are unknown. Unlike previous work, the algorithm categorizes word tokens in context instead of word types. The algorithm is evaluated on the Brown Corpus. | The present paper is concerned with tagging languages and sublanguages for which no a priori knowledge about grammatical categories is available, a situation that occurs often in practice @cite_4 . | {
"cite_N": [
"@cite_4"
],
"mid": [
"144990771"
],
"abstract": [
"In this paper, we will discuss a method for assigning part of speech tags to words in an unannotated text corpus whose structure is completely unknown, with a little bit of help from an informant. Starting from scratch, automated an... |
cmp-lg9503009 | 2951769629 | This paper presents an algorithm for tagging words whose part-of-speech properties are unknown. Unlike previous work, the algorithm categorizes word tokens in context instead of word types. The algorithm is evaluated on the Brown Corpus. | In a previous paper @cite_15 , we trained a neural network to disambiguate part-of-speech using context; however, no information about the word that is to be categorized was used. This scheme fails for cases like The soldiers rarely come home.'' vs. The soldiers will come home.'' where the context is identical and information about the lexical item in question ( rarely'' vs. will'') is needed in combination with context for correct classification. In this paper, we will compare two tagging algorithms, one based on classifying word types, and one based on classifying words-plus-context. | {
"cite_N": [
"@cite_15"
],
"mid": [
"2163514362"
],
"abstract": [
"This paper presents a method for inducing the parts of speech of a language and part-of-speech labels for individual words from a large text corpus. Vector representations for the part-of-speech of a word are formed from entries o... |
cmp-lg9607020 | 1497662183 | In this paper, we propose a novel strategy which is designed to enhance the accuracy of the parser by simplifying complex sentences before parsing. This approach involves the separate parsing of the constituent sub-sentences within a complex sentence. To achieve that, the divide-and-conquer strategy first disambiguates the roles of the link words in the sentence and segments the sentence based on these roles. The separate parse trees of the segmented sub-sentences and the noun phrases within them are then synthesized to form the final parse. To evaluate the effects of this strategy on parsing, we compare the original performance of a dependency parser with the performance when it is enhanced with the divide-and-conquer strategy. When tested on 600 sentences of the IPSM'95 data sets, the enhanced parser saw a considerable error reduction of 21.2 in its accuracy. | Magerman discussed the poor performance of his parser SPATTER on sentences with conjunctions @cite_9 . As a result, he augmented SPATTER's probabilistic model with an additional conjunction feature. However, he reported that though SPATTER's performance on conjoined sentences improves with the conjunction feature, a significant percentage is still misanalyzed, as the simple conjunction feature model finds it difficult to capture long distance dependencies. | {
"cite_N": [
"@cite_9"
],
"mid": [
"1924403233"
],
"abstract": [
"Traditional natural language parsers are based on rewrite rule systems developed in an arduous, time-consuming manner by grammarians. A majority of the grammarian's efforts are devoted to the disambiguation process, first hypothesi... |
cmp-lg9607020 | 1497662183 | In this paper, we propose a novel strategy which is designed to enhance the accuracy of the parser by simplifying complex sentences before parsing. This approach involves the separate parsing of the constituent sub-sentences within a complex sentence. To achieve that, the divide-and-conquer strategy first disambiguates the roles of the link words in the sentence and segments the sentence based on these roles. The separate parse trees of the segmented sub-sentences and the noun phrases within them are then synthesized to form the final parse. To evaluate the effects of this strategy on parsing, we compare the original performance of a dependency parser with the performance when it is enhanced with the divide-and-conquer strategy. When tested on 600 sentences of the IPSM'95 data sets, the enhanced parser saw a considerable error reduction of 21.2 in its accuracy. | Jones explored another type of link words, the punctuations @cite_7 . He showed successfully that for longer sentences, a grammar which makes use of punctuation massively outperforms one which does not. Besides improving parsing accuracy, the use of punctuations also significantly reduces the number of possible parses generated. However, as theoretical forays into the syntactic roles of punctuation are limited, the grammar he designed can only cover a subset of all punctuation phenomena. Unexpected constructs thus cause the grammar to fail completely. | {
"cite_N": [
"@cite_7"
],
"mid": [
"2039117335"
],
"abstract": [
"Few, if any, current NLP systems make any significant use of punctuation. Intuitively, a treatment of punctuation seems necessary to the analysis and production of text. Whilst this has been suggested in the fields of discourse str... |
1908.11823 | 2970705892 | In this work we investigate to which extent one can recover class probabilities within the empirical risk minimization (ERM) paradigm. The main aim of our paper is to extend existing results and emphasize the tight relations between empirical risk minimization and class probability estimation. Based on existing literature on excess risk bounds and proper scoring rules, we derive a class probability estimator based on empirical risk minimization. We then derive fairly general conditions under which this estimator will converge, in the L1-norm and in probability, to the true class probabilities. Our main contribution is to present a way to derive finite sample L1-convergence rates of this estimator for different surrogate loss functions. We also study in detail which commonly used loss functions are suitable for this estimation problem and finally discuss the setting of model-misspecification as well as a possible extension to asymmetric loss functions. | perform an analysis similar to ours as they also investigate convergence properties of a class probability estimator, their start and end point are very different though. While we start with theory from proper scoring rules, their paper directly starts with the class probability estimator as found in @cite_5 . The problem is that the estimator in @cite_5 only appears as a side remark, and it is unclear to which extent this is the best, only or even the correct choice. This paper contributes to close this gap and answers those questions. They show that the estimator converges to a unique class probability model. In relation to this one can view this paper as an investigation of this unique class probability model and we give necessary and sufficient conditions that lead to convergence to the true class probabilities. Note also that their paper uses convex methods, while our work in comparison draws from the theory of proper scoring rules. | {
"cite_N": [
"@cite_5"
],
"mid": [
"2023163512"
],
"abstract": [
"We study how closely the optimal Bayes error rate can be approximately reached using a classification algorithm that computes a classifier by minimizing a convex upper bound of the classification error function. The measurement of ... |
1908.11823 | 2970705892 | In this work we investigate to which extent one can recover class probabilities within the empirical risk minimization (ERM) paradigm. The main aim of our paper is to extend existing results and emphasize the tight relations between empirical risk minimization and class probability estimation. Based on existing literature on excess risk bounds and proper scoring rules, we derive a class probability estimator based on empirical risk minimization. We then derive fairly general conditions under which this estimator will converge, in the L1-norm and in probability, to the true class probabilities. Our main contribution is to present a way to derive finite sample L1-convergence rates of this estimator for different surrogate loss functions. We also study in detail which commonly used loss functions are suitable for this estimation problem and finally discuss the setting of model-misspecification as well as a possible extension to asymmetric loss functions. | The probability estimator we use also appears in @cite_10 where it is used to derive excess risk bounds, referred to as surrogate risk bounds, for bipartite ranking. The methods used are very similar in the sense that these are also based on proper scoring rules. The difference is again the focus, and even more so the conditions used. They introduce the notion of strongly proper scoring rules which directly allows one to bound the @math -norm, and thus the @math -norm, of the estimator in terms of the excess risk. We show that convergence can be achieved already under milder conditions. We then use the concept of modulus of continuity, of which strongly proper scoring rules are a particular case, to analyze the rate of convergence. | {
"cite_N": [
"@cite_10"
],
"mid": [
"2141789531"
],
"abstract": [
"The problem of bipartite ranking, where instances are labeled positive or negative and the goal is to learn a scoring function that minimizes the probability of mis-ranking a pair of positive and negative instances (or equivalentl... |
1908.11829 | 2970633507 | We consider the minimum cut problem in undirected, weighted graphs. We give a simple algorithm to find a minimum cut that @math -respects (cuts two edges of) a spanning tree @math of a graph @math . This procedure can be used in place of the complicated subroutine given in Karger's near-linear time minimum cut algorithm (J. ACM, 2000). We give a self-contained version of Karger's algorithm with the new procedure, which is easy to state and relatively simple to implement. It produces a minimum cut on an @math -edge, @math -vertex graph in @math time with high probability. This performance matches that achieved by Karger, thereby matching the current state of the art. | On an unweighted graph, Gabow @cite_13 showed how to compute the minimum cut in @math time, where @math is the capacity of the minimum cut. Karger @cite_29 improved Gabow's algorithm by applying random sampling, achieving runtime @math The @math notation hides @math factors. Las Vegas. The sampling technique developed by Karger @cite_29 , combined with the tree-packing technique devised by Gabow @cite_13 , form the basis of Karger's near-linear time minimum cut algorithm @cite_16 . As previously mentioned, this technique finds the minimum cut in an undirected, weighted graph in @math time with high probability. | {
"cite_N": [
"@cite_29",
"@cite_16",
"@cite_13"
],
"mid": [
"2150516767",
"1964510837",
"2012287357"
],
"abstract": [
"We use random sampling as a tool for solving undirected graph problems. We show that the sparse graph, or skeleton, that arises when we randomly sample a graph's ... |
1908.11829 | 2970633507 | We consider the minimum cut problem in undirected, weighted graphs. We give a simple algorithm to find a minimum cut that @math -respects (cuts two edges of) a spanning tree @math of a graph @math . This procedure can be used in place of the complicated subroutine given in Karger's near-linear time minimum cut algorithm (J. ACM, 2000). We give a self-contained version of Karger's algorithm with the new procedure, which is easy to state and relatively simple to implement. It produces a minimum cut on an @math -edge, @math -vertex graph in @math time with high probability. This performance matches that achieved by Karger, thereby matching the current state of the art. | A recent development uses low-conductance cuts to find the minimum cut in an undirected unweighted graph. This technique was introduced by Kawarabayashi and Thorup @cite_2 , who achieve near-linear deterministic time (estimated to be @math ). This was improved by Henzinger, Rao, and Wang @cite_31 , who achieve deterministic runtime @math . Although the algorithm of is more efficient than Karger's algorithm @cite_16 on unweighted graphs, the procedure, as well as the one it was based on @cite_2 are quite involved, thus making them largely impractical for implementation purposes. | {
"cite_N": [
"@cite_31",
"@cite_16",
"@cite_2"
],
"mid": [
"2569104968",
"1964510837",
"2963972775"
],
"abstract": [
"We study the problem of computing a minimum cut in a simple, undirected graph and give a deterministic O(m log2 n log log2 n) time algorithm. This improves both on... |
1908.11656 | 2971124296 | We propose LU-Net -- for LiDAR U-Net, a new method for the semantic segmentation of a 3D LiDAR point cloud. Instead of applying some global 3D segmentation method such as PointNet, we propose an end-to-end architecture for LiDAR point cloud semantic segmentation that efficiently solves the problem as an image processing problem. We first extract high-level 3D features for each point given its 3D neighbors. Then, these features are projected into a 2D multichannel range-image by considering the topology of the sensor. Thanks to these learned features and this projection, we can finally perform the segmentation using a simple U-Net segmentation network, which performs very well while being very efficient. In this way, we can exploit both the 3D nature of the data and the specificity of the LiDAR sensor. This approach outperforms the state-of-the-art by a large margin on the KITTI dataset, as our experiments show. Moreover, this approach operates at 24fps on a single GPU. This is above the acquisition rate of common LiDAR sensors which makes it suitable for real-time applications. | Semantic segmentation of images has been the subject of many works in the past years. Recently, deep learning methods have largely outperformed previous ones. The method presented in @cite_16 was the first to propose an accurate end-to-end network for semantic segmentation. This method is based on an encoder in which each scale is used to compute the final segmentation. Only a few month later, the U-Net architecture @cite_20 was proposed for the semantic segmentation of medical images. This method is an encoder-decoder able to provide highly precise segmentation. These two methods have largely influenced recent works such as DeeplabV3+ @cite_11 that uses dilated convolutional layers and spatial pyramid pooling modules in an encoder-decoder structure to improve the quality of the prediction. Other approaches explore multi-scale architectures to produce and fuse segmentations performed at different scales @cite_15 @cite_7 . Most of these methods are able to produce very accurate results, on various types of images (medical, outdoor, indoor). The survey @cite_1 of CNNs methods for semantic segmentation provides a deep analysis of some recent techniques. This work demonstrates that a combination of various components would most likely improve segmentation results on wider classes of objects. | {
"cite_N": [
"@cite_7",
"@cite_1",
"@cite_15",
"@cite_16",
"@cite_20",
"@cite_11"
],
"mid": [
"2611259176",
"2898743055",
"2563705555",
"1903029394",
"1901129140",
"2964309882"
],
"abstract": [
"We focus on the challenging task of real-time semantic segment... |
1908.11656 | 2971124296 | We propose LU-Net -- for LiDAR U-Net, a new method for the semantic segmentation of a 3D LiDAR point cloud. Instead of applying some global 3D segmentation method such as PointNet, we propose an end-to-end architecture for LiDAR point cloud semantic segmentation that efficiently solves the problem as an image processing problem. We first extract high-level 3D features for each point given its 3D neighbors. Then, these features are projected into a 2D multichannel range-image by considering the topology of the sensor. Thanks to these learned features and this projection, we can finally perform the segmentation using a simple U-Net segmentation network, which performs very well while being very efficient. In this way, we can exploit both the 3D nature of the data and the specificity of the LiDAR sensor. This approach outperforms the state-of-the-art by a large margin on the KITTI dataset, as our experiments show. Moreover, this approach operates at 24fps on a single GPU. This is above the acquisition rate of common LiDAR sensors which makes it suitable for real-time applications. | Recently, SqueezeSeg, a novel approach for the semantic segmentation of a LiDAR point cloud represented as a spherical range-image @cite_14 , was proposed. This representation allows to perform the segmentation by using simple 2D convolutions, which lowers the computational cost while keeping good accuracy. The architecture is derived from the SqueezeNet image segmentation method @cite_13 . The intermediate layers are "fire layers", layers made of one squeeze module and one expansion module. Later on, the same authors improved this method in @cite_3 by adding a context aggregation module and by considering focal loss and batch normalization to improve the quality of the segmentation. A similar range-image approach was proposed in @cite_17 , where a Atrous Spatial Pyramid Pooling @cite_4 and squeeze reweighting layer @cite_8 are added. Finally, in @cite_10 , the authors offer to input a range-image directly to the U-Net architecture described in @cite_20 . This method achieves results that are comparable to the state of the art of range-image methods with a much simpler and more intuitive architecture. All these range-image methods succeed in real-time computation. However, their results often lack of accuracy which limits their usage in real scenarios. | {
"cite_N": [
"@cite_14",
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"abstract": [
"",
"In this... |
1908.11769 | 2971290534 | Rewriting logic is naturally concurrent: several subterms of the state term can be rewritten simultaneously. But state terms are global, which makes compositionality difficult to achieve. Compositionality here means being able to decompose a complex system into its functional components and code each as an isolated and encapsulated system. Our goal is to help bringing compositionality to system specification in rewriting logic. The base of our proposal is the operation that we call synchronous composition. We discuss the motivations and implications of our proposal, formalize it for rewriting logic and also for transition structures, to be used as semantics, and show the power of our approach with some examples. This paper is under consideration in Theory and Practice of Logic Programming (TPLP). | Several temporal logics have been proposed that make joint use of actions and propositions on states: ACTL* @cite_34 , RLTL @cite_0 , SE-LTL @cite_4 , TLR* @cite_25 . There are also transition structures with mixed ingredients: LKS @cite_4 , L2TS @cite_54 . Although all of them bring actions (or transitions) to the focus, none tries to be utterly egalitarian, as we do. | {
"cite_N": [
"@cite_4",
"@cite_54",
"@cite_0",
"@cite_34",
"@cite_25"
],
"mid": [
"",
"2167352300",
"2024215898",
"1602925513",
"1599831144"
],
"abstract": [
"",
"Three temporal logics are introduced which induce on labeled transition systems the same identific... |
End of preview. Expand
in Data Studio
This is a copy of the Multi-XScience dataset, except the input source documents of its test split have been replaced by a sparse retriever. The retrieval pipeline used:
- query: The
related_workfield of each example - corpus: The union of all documents in the
train,validationandtestsplits - retriever: BM25 via PyTerrier with default settings
- top-k strategy:
"max", i.e. the number of documents retrieved,k, is set as the maximum number of documents seen across examples in this dataset, in this casek==20
Retrieval results on the train set:
| Recall@100 | Rprec | Precision@k | Recall@k |
|---|---|---|---|
| 0.5482 | 0.2243 | 0.0547 | 0.4063 |
Retrieval results on the validation set:
| Recall@100 | Rprec | Precision@k | Recall@k |
|---|---|---|---|
| 0.5476 | 0.2209 | 0.0553 | 0.4026 |
Retrieval results on the test set:
| Recall@100 | Rprec | Precision@k | Recall@k |
|---|---|---|---|
| 0.5480 | 0.2272 | 0.055 | 0.4039 |
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