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Full-Text Articles in Physical Sciences and Mathematics
Proofs Of Soundness And Strong Normalization For Linear Memory Types, Heng Huang, Chris Hawblitzel
Proofs Of Soundness And Strong Normalization For Linear Memory Types, Heng Huang, Chris Hawblitzel
Computer Science Technical Reports
Efficient low-level systems need more control over memory than safe high-level languages usually provide. As a result, run-time systems are typically written in unsafe languages such as C. This report describes an abstract machine designed to give type-safe code more control over memory. It includes complete definitions and proofs.
Exact Formulae For The Lovasz Theta Function Of Sparse Circulant Graphs, Valentino Crespi
Exact Formulae For The Lovasz Theta Function Of Sparse Circulant Graphs, Valentino Crespi
Computer Science Technical Reports
The Lovasz theta function has attracted a lot of attention for its connection with diverse issues, such as communicating without errors and computing large cliques in graphs. Indeed this function enjoys the remarkable property of being computable in polynomial time, despite being sandwitched between clique and chromatic number, two well known hard to compute quantities. In this paper I provide a closed formula for the Lovasz function of a specific class of sparse circulant graphs thus generalizing Lovasz results on cycle graphs (circulant graphs of degree 2).
Distributed Algorithms For Guiding Navigation Across A Sensor Network, Qun Li, Michael Derosa, Daniela Rus
Distributed Algorithms For Guiding Navigation Across A Sensor Network, Qun Li, Michael Derosa, Daniela Rus
Computer Science Technical Reports
We develop distributed algorithms for self-reconfiguring sensor networks that respond to directing a target through a region. The sensor network models the danger levels sensed across its area and has the ability to adapt to changes. It represents the dangerous areas as obstacles. A protocol that combines the artificial potential field of the sensors with the goal location for the moving object guides the object incrementally across the network to the goal, while maintaining the safest distance to the danger areas. We report on hardware experiments using a physical sensor network consisting of Mote sensors.
Using The Emulab Network Testbed To Evaluate The Armada I/O Framework For Computational Grids, Ron Oldfield, David Kotz
Using The Emulab Network Testbed To Evaluate The Armada I/O Framework For Computational Grids, Ron Oldfield, David Kotz
Computer Science Technical Reports
This short report describes our experiences using the Emulab network testbed at the University of Utah to test performance of the Armada framework for parallel I/O on computational grids.
Heterogeneous Self-Reconfiguring Robotics: Ph.D. Thesis Proposal, Robert C. Fitch
Heterogeneous Self-Reconfiguring Robotics: Ph.D. Thesis Proposal, Robert C. Fitch
Computer Science Technical Reports
Self-reconfiguring robots are modular systems that can change shape, or "reconfigure," to match structure to task. They comprise many small, discrete, often identical modules that connect together and that are minimally actuated. Global shape transformation is achieved by composing local motions. Systems with a single module type, known as "homogeneous" systems, gain fault tolerance, robustness and low production cost from module interchangeability. However, we are interested in "heterogeneous" systems, which include multiple types of modules such as those with sensors, batteries or wheels. We believe that heterogeneous systems offer the same benefits as homogeneous systems with the added ability to …
Analysis Of A Campus-Wide Wireless Network, David Kotz, Kobby Essien
Analysis Of A Campus-Wide Wireless Network, David Kotz, Kobby Essien
Computer Science Technical Reports
Understanding usage patterns in wireless local-area networks (WLANs) is critical for those who develop, deploy, and manage WLAN technology, as well as those who develop systems and application software for wireless networks. This paper presents results from the largest and most comprehensive trace of network activity in a large, production wireless LAN. For eleven weeks we traced the activity of nearly two thousand users drawn from a general campus population, using a campus-wide network of 476 access points spread over 161 buildings. Our study expands on those done by Tang and Baker, with a significantly larger and broader population. We …
Xslt And Xquery As Operator Languages, A Abram White
Xslt And Xquery As Operator Languages, A Abram White
Computer Science Technical Reports
Ubiquitous computing promises to integrate computers into our physical environment, surrounding us with applications that are able to adapt to our dynamics. Solar is a software infrastructure designed to deliver contextual information to these applications. Solar represents context data as events, and uses small programs called operators to filter, merge, aggregate, or transform event streams. This paper explores the possibility of using XSLT and XQuery to build language-neutral Solar operators.
Characterizing Usage Of A Campus-Wide Wireless Network, David Kotz, Kobby Essien
Characterizing Usage Of A Campus-Wide Wireless Network, David Kotz, Kobby Essien
Computer Science Technical Reports
Wireless local-area networks (WLANs) are increasingly common, but little is known about how they are used. A clear understanding of usage patterns in real WLANs is critical information to those who develop, deploy, and manage WLAN technology, as well as those who develop systems and application software for wireless networks. This paper presents results from the largest and most comprehensive trace of network activity in a large, production wireless LAN. For eleven weeks we traced the activity of nearly two thousand users drawn from a general campus population, using a campus-wide network of 476 access points spread over 161 buildings. …
Controlling Access To Pervasive Information In The “Solar” System, Kazuhiro Minami, David Kotz
Controlling Access To Pervasive Information In The “Solar” System, Kazuhiro Minami, David Kotz
Computer Science Technical Reports
Pervasive-computing infrastructures necessarily collect a lot of context information to disseminate to their context-aware applications. Due to the personal or proprietary nature of much of this context information, however, the infrastructure must limit access to context information to authorized persons. In this paper we propose a new access-control mechanism for event-based context-distribution infrastructures. The core of our approach is based on a conservative information-flow model of access control, but users may express discretionary relaxation of the resulting access-control list (ACL) by specifying relaxation functions. This combination of automatic ACL derivation and user-specified ACL relaxation allows access control to be determined …
Context Aggregation And Dissemination In Ubiquitous Computing Systems, Guanling Chen, David Kotz
Context Aggregation And Dissemination In Ubiquitous Computing Systems, Guanling Chen, David Kotz
Computer Science Technical Reports
Many ``ubiquitous computing'' applications need a constant flow of information about their environment to be able to adapt to their changing context. To support these ``context-aware'' applications we propose a graph-based abstraction for collecting, aggregating, and disseminating context information. The abstraction models context information as events, produced by sources and flowing through a directed acyclic graph of event-processing operators and delivered to subscribing applications. Applications describe their desired event stream as a tree of operators that aggregate low-level context information published by existing sources into the high-level context information needed by the application. The operator graph is thus the dynamic …
Solar: A Pervasive-Computing Infrastructure For Context-Aware Mobile Applications, Guanling Chen, David Kotz
Solar: A Pervasive-Computing Infrastructure For Context-Aware Mobile Applications, Guanling Chen, David Kotz
Computer Science Technical Reports
Emerging pervasive computing technologies transform the way we live and work by embedding computation in our surrounding environment. To avoid increasing complexity, and allow the user to concentrate on her tasks, applications must automatically adapt to their changing \emph{context}, the physical and computational environment in which they run. To support these ``context-aware'' applications we propose a graph-based abstraction for collecting, aggregating, and disseminating context information. The abstraction models context information as \emph{events}, which are produced by \emph{sources}, flow through a directed acyclic graph of event-processing \emph{operators}, and are delivered to subscribing applications. Applications describe their desired event stream as a …
Virtual Hierarchies - An Architecture For Building And Maintaining Efficient And Resilient Trust Chains, John Marchesini, Sean Smith
Virtual Hierarchies - An Architecture For Building And Maintaining Efficient And Resilient Trust Chains, John Marchesini, Sean Smith
Computer Science Technical Reports
In Public Key Infrastructure (PKI), the simple, monopolistic CA model works fine until we consider the real world. Then, issues such as scalability and mutually suspicious organizations create the need for a multiplicity of CAs, which immediately introduces the problem of how to organize them to balance resilience to compromise against efficiency of path discovery. However, security has given us tools such as secure coprocessing, secret splitting, secret sharing, and threshold cryptography for securely carrying out computations among multiple trust domains; distributed computing has given us peer-to-peer networking, for creating self-organizing distributed systems. In this paper, we use these latter …
Trusted Paths For Browsers: An Open-Source Solution To Web Spoofing, Zishuang (Eileen) Ye, Sean Smith
Trusted Paths For Browsers: An Open-Source Solution To Web Spoofing, Zishuang (Eileen) Ye, Sean Smith
Computer Science Technical Reports
The security of the vast majority of ``secure'' Web services rests on SSL server PKI. However, this PKI doesn't work if the the adversary can trick the browser into appearing to tell the user the wrong thing about the certificates and cryptography. The seminal web spoofing work of Felten et al demonstrated the potential, in 1996, for malicious servers to impersonate honest servers. Our recent follow-up work explicitly shows how malicious servers can still do this---and can also forge the existence of an SSL session and the contents of the alleged server certificate. This paper reports the results of our …
Ffts For The 2-Sphere - Improvements And Variations, D M. Healy Jr, D N. Rockmore, P J. Kostelec, Sean S.B. Moore
Ffts For The 2-Sphere - Improvements And Variations, D M. Healy Jr, D N. Rockmore, P J. Kostelec, Sean S.B. Moore
Computer Science Technical Reports
Earlier work by Driscoll and Healy has produced an efficient algorithm for computing the Fourier transform of band-limited functions on the 2-sphere. In this paper we present a reformulation and variation of the original algorithm which results in a greatly improved inverse transform, and consequent improved convolution algorithm for such functions. All require at most $O(N\log^2 N)$ operations where $N$ is the number of sample points. We also address implementation considerations and give heuristics for allowing reliable and computationally efficient floating point implementations of slightly modified algorithms. These claims are supported by extensive numerical experiments from our implementation in C …
Web Spoofing Revisited: Ssl And Beyond, Eileen Zishuang Ye, Yougu Yuan, Sean Smith
Web Spoofing Revisited: Ssl And Beyond, Eileen Zishuang Ye, Yougu Yuan, Sean Smith
Computer Science Technical Reports
Can users believe what their browsers tell them? Even sophisticated Web users decide whether or not to trust a server based on browser cues such as location bar information, SSL icons, SSL warnings, certificate information, and response time. In their seminal work on Web spoofing, Felten et al showed how, in 1996, a malicious server could forge some of these cues. However, this work used genuine SSL sessions, and Web technology has evolved much since 1996. The Web has since become the pre-eminent medium for electronic service delivery to remote users, and the security of many commerce, government, and academic …
Future Directions For Mobile-Agent Research, David Kotz, Robert Gray, Daniela Rus
Future Directions For Mobile-Agent Research, David Kotz, Robert Gray, Daniela Rus
Computer Science Technical Reports
During a discussion in September 2000 the authors examined the future of research on mobile agents and mobile code. (A mobile agent is a running program that can move from host to host in network at times and to places of its own choosing.) In this paper we summarize and reflect on that discussion. It became clear that the field should shift its emphasis toward mobile code, in all its forms, rather than to continue its narrow focus on mobile agents. Furthermore, we encourage the development of modular components, so that application designers may take advantage of code mobility without …
Tr-2002005: Towards A Theory Of Social Software, Rohit Parikh
Tr-2002005: Towards A Theory Of Social Software, Rohit Parikh
Computer Science Technical Reports
No abstract provided.
Tr-2002006: States Of Knowledge, Rohit Parikh
Tr-2002006: States Of Knowledge, Rohit Parikh
Computer Science Technical Reports
No abstract provided.
Tr-2002004: On The Effectiveness Of Tangible Interfaces In Collaborative Learning Environments, Lori L. Scarlatos, Shalva S. Landy, Julia Breban, Robin Horowitz, Chanie Sandberg
Tr-2002004: On The Effectiveness Of Tangible Interfaces In Collaborative Learning Environments, Lori L. Scarlatos, Shalva S. Landy, Julia Breban, Robin Horowitz, Chanie Sandberg
Computer Science Technical Reports
No abstract provided.
Tr-2002001: Can We Optimize Toeplitz/Hankel Computations?, V. Y. Pan
Tr-2002001: Can We Optimize Toeplitz/Hankel Computations?, V. Y. Pan
Computer Science Technical Reports
No abstract provided.
Tr-2002007: Ubiquitous Puzzle Pieces: 3d Tangible Interfaces For Collaborative Learning Environments, Lori L. Scarlatos, Shalva S. Landy, Saira Qureshi
Tr-2002007: Ubiquitous Puzzle Pieces: 3d Tangible Interfaces For Collaborative Learning Environments, Lori L. Scarlatos, Shalva S. Landy, Saira Qureshi
Computer Science Technical Reports
No abstract provided.
Tr-2002002: Can We Optimize Toeplitz/Hankel Computations? Ii. Singular Toeplitz/Hankel-Like Case, V. Y. Pan
Tr-2002002: Can We Optimize Toeplitz/Hankel Computations? Ii. Singular Toeplitz/Hankel-Like Case, V. Y. Pan
Computer Science Technical Reports
No abstract provided.
Tr-2002008: Investigation Of The Sensitivity Of The Monte Carlo Solution For The Barker-Ferry Equation Using Different Sequential And Parallel Pseudo-Random Number Generators, T. V. Gurov, P. A. Whitlock
Tr-2002008: Investigation Of The Sensitivity Of The Monte Carlo Solution For The Barker-Ferry Equation Using Different Sequential And Parallel Pseudo-Random Number Generators, T. V. Gurov, P. A. Whitlock
Computer Science Technical Reports
No abstract provided.
Tr-2002010: Programming Finite-Domain Constraint Propagators In Action Rules, Neng-Fa Zhou
Tr-2002010: Programming Finite-Domain Constraint Propagators In Action Rules, Neng-Fa Zhou
Computer Science Technical Reports
No abstract provided.
Tr-2002011: Corpus-Based Ambiguity Resolution Of Biomedical Terms Using Knowledge Bases And Machine Learning, Hongfang Liu
Tr-2002011: Corpus-Based Ambiguity Resolution Of Biomedical Terms Using Knowledge Bases And Machine Learning, Hongfang Liu
Computer Science Technical Reports
No abstract provided.
Tr-2002018: How Frequently Is A Matrix Nonsingular?, Xinmao Wang
Tr-2002018: How Frequently Is A Matrix Nonsingular?, Xinmao Wang
Computer Science Technical Reports
No abstract provided.
Tr-2002019: Improved Algorithms For Computing Determinants And Resultants, Ioannis Z. Emiris, Victor Y. Pan
Tr-2002019: Improved Algorithms For Computing Determinants And Resultants, Ioannis Z. Emiris, Victor Y. Pan
Computer Science Technical Reports
No abstract provided.
Tr-2002020: Inverse Power And Durand-Kerner Iterations For Univariate Polynomial Root-Finding, D. A. Bini, L. Gemignani, V. Y. Pan
Tr-2002020: Inverse Power And Durand-Kerner Iterations For Univariate Polynomial Root-Finding, D. A. Bini, L. Gemignani, V. Y. Pan
Computer Science Technical Reports
No abstract provided.
Tr-2002015: Residual Correction Algorithms For General And Structured Matrices, V. Y. Pan, M. Kunin, R. E. Rosholt, H. Cebecioglu
Tr-2002015: Residual Correction Algorithms For General And Structured Matrices, V. Y. Pan, M. Kunin, R. E. Rosholt, H. Cebecioglu
Computer Science Technical Reports
No abstract provided.
Tr-2002003: Univariate Polynomial Root-Finding With A Lower Computational Precision And Higher Convergence Rates, V. Y. Pan
Computer Science Technical Reports
No abstract provided.