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Full-Text Articles in Physical Sciences and Mathematics
Linear Least-Squares Algorithms For Temporal Difference Learning, Steven J. Bradtke, Andrew G. Barto
Linear Least-Squares Algorithms For Temporal Difference Learning, Steven J. Bradtke, Andrew G. Barto
Computer Science Department Faculty Publication Series
We introduce two new temporal difference (TD) algorithms based on the theory of linear leastsquares function approximation. We define an algorithm we call Least-Squares TD (LS TD) for which we prove probability-one convergence when it is used with a function approximator linear in the adjustable parameters. We then define a recursive version of this algorithm, Recursive Least-Squares TD (RLS TD). Although these new TD algorithms require more computation per time-step than do Sutton's TD(A) algorithms, they are more efficient in a statistical sense because they extract more information from training experiences. We describe a simulation experiment showing the substantial improvement …
An Evaluation Of Techniques For Clustering Search Results, W. Bruce Croft, Anton V. Leouski
An Evaluation Of Techniques For Clustering Search Results, W. Bruce Croft, Anton V. Leouski
Computer Science Department Faculty Publication Series
The ability to effectively organize retrieval results becomes more important as the focus of Information Retrieval (IR) shifts towards interactive search processes. Automatic classification techniques are capable of providing the necessary information organization by arranging the retrieved data into groups of documents with common subjects. In this paper, we compare classification methods from IR and Machine Learning (ML) for clustering search results. Issues such as document representation, classification algorithms, and cluster representation are discussed. We introduce several evaluation techniques and use them in preliminary experiments. These experiments indicate that the proposed techniques have promise, but it is clear that user …
Using Reflection To Support Type-Safe Evolution In Persistent Systems, G.N.C. Kirby
Using Reflection To Support Type-Safe Evolution In Persistent Systems, G.N.C. Kirby
Computer Science Department Faculty Publication Series
Reflection has been used to address many different problem areas, and the term reflection has itself been used to describe several distinct processes. This paper identifies three simple operations, generation, raising and dynamic rebinding, which may be composed to yield several varieties of reflection. These can be used to allow a self-contained programming system to evolve, through the incorporation of new behaviour into either the application programs or the interpreter which controls their execution. Reflection is a powerful mechanism and potentially dangerous. Used in the context of persistent programming systems, safety is an important consideration: the integrity of large amounts …
Improving Data Locality With Loop Transformations, Kathryn S. Mckinley, Steve Carr, Chau-Wen Tseng
Improving Data Locality With Loop Transformations, Kathryn S. Mckinley, Steve Carr, Chau-Wen Tseng
Computer Science Department Faculty Publication Series
In the past decade, processor speed has become significantly faster than memory speed. Small, fast cache memories are designed to overcome this discrepancy, but they are only effective when programs exhibit data locality. In this article, we present compiler optimizations to improve data locality based on a simple yet accurate cost model. The model computes both temporal and spatial reuse of cache lines to find desirable loop organizations. The cost model drives the application of compound transformations consisting of loop permutation, loop fusion, loop distribution, and loop reversal. We demonstrate that these program transformations are useful for optimizing many programs. …
Real-Time And Embedded Systems, John A. Stankovic
Real-Time And Embedded Systems, John A. Stankovic
Computer Science Department Faculty Publication Series
No abstract provided.
Indexing Handwriting Using Word Matching, R. Manmatha
Indexing Handwriting Using Word Matching, R. Manmatha
Computer Science Department Faculty Publication Series
There are many historical manuscripts written in a single hand which it would be useful to index. Examples include theW. B. DuBois collection at theUniversity ofMassachusetts and the early Presidential libraries at the Library of Congress. The standard technique for indexing documents is to scan them in, convert them to machine readable form (ASCII) using Optical Character Recognition (OCR) and then index them using a text retrieval engine. However, OCR does not work well on handwriting. Here an alternative scheme is proposed for indexing such texts. Each page of the document is segmented into words. The images of the words …
Improving The Accuracy Of Petri Net-Based Analysis Of Concurrent Programs, A. T. Chamillard, Lori A. Clarke
Improving The Accuracy Of Petri Net-Based Analysis Of Concurrent Programs, A. T. Chamillard, Lori A. Clarke
Computer Science Department Faculty Publication Series
Spurious results are an inherent problem of most static analysis methods. These methods, in an effort to produce conservative results, overestimate the executable behavior of a program. Infeasible paths and imprecise alias resolution are the two causes of such inaccuracies. In this paper we present an approach for improving the accuracy of Petri net-based analysis of concurrent programs by including additional program state information in the Petri net. We present empirical results that demonstrate the improvements in accuracy and, in some cases, the reduction in the search space that result from applying this approach to concurrent Ada programs.
Tracking Object Motion Across Aspect Changes For Augmented Reality, S. Ravela
Tracking Object Motion Across Aspect Changes For Augmented Reality, S. Ravela
Computer Science Department Faculty Publication Series
A model registration system capable of tracking an object through distinct aspects in real-time is presented. The system integrates tracking, pose determination, and aspect graph indexing. The tracking combines steerable filters with normalized cross-correlation, compensates for rotation in 2D and is adaptive. Robust statistical methods are used in the pose estimation to detect and remove mismatches. The aspect graph is used to determine when features will disappear or become difficult to track an dto predict when and where new features will become trackable. The overall system is stable and is amenable to real-time performance.
Learning Situation-Specific Coordination In Generalized Partial Global Planning, M. V. Nagendra Prasad, Victor R. Lesser
Learning Situation-Specific Coordination In Generalized Partial Global Planning, M. V. Nagendra Prasad, Victor R. Lesser
Computer Science Department Faculty Publication Series
No abstract provided.
Execution Performance Issues In Full-Text Information Retrieval, Eric W. Brown
Execution Performance Issues In Full-Text Information Retrieval, Eric W. Brown
Computer Science Department Faculty Publication Series
The task of an information retrieval system is to identify documents that will satisfy a user’s information need. Effective fulfillment of this task has long been an active area of research, leading to sophisticated retrieval models for representing information content in documents and queries and measuring similarity between the two. The maturity and proven effectiveness of these systems has resulted in demand for increased capacity, performance, scalability, and functionality, especially as information retrieval is integrated into more traditional database management environments. In this dissertation we explore a number of functionality and performance issues in information retrieval. First, we consider creation …
Packet Loss Correlation In The Mbone Multicast Network, Maya Yajnik, Jim Kurose, Don Towsley
Packet Loss Correlation In The Mbone Multicast Network, Maya Yajnik, Jim Kurose, Don Towsley
Computer Science Department Faculty Publication Series
The recent success ofmulticast applications such as Internet teleconferencing illustrates the tremendous potential of applications built upon wide-area multicast communication services. A critical issue for such multicast applications and the higher layer protocols required to support them is the manner in which packet losses occur within the multicast network. In this paper we present and analyze packet loss data collected on multicast-capable hosts at 17 geographically distinct locations in Europe and the US and connected via the MBone. We experimentally and quantitatively examine the spatial and temporal correlation in packet loss among participants in a multicast session. Our results show …
Knowledge-Directed Vision: Control, Learning, And Integration, Bruce A. Draper, Allen R. Hanson, Edward M. Riseman
Knowledge-Directed Vision: Control, Learning, And Integration, Bruce A. Draper, Allen R. Hanson, Edward M. Riseman
Computer Science Department Faculty Publication Series
The knowledge-directed approach to image interpretation, popular in the 1980's, sought to identify objects in unconstrained two-dimensional images and to determine the threedimensional relationships between these objects and the camera by applying large amounts of object- and domain-specific knowledge to the interpretation problem. Among the primary issues faced by these systems were variations among instances of an object class and differences in how object classes were defined in terms of shape, color, function, texture, size, and/or substructures. This paper argues that knowledge-directed vision systems typically failed for two reasons. The first is that the low- and mid-level vision procedures that …