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Articles 1 - 7 of 7
Full-Text Articles in Physical Sciences and Mathematics
An Access-Control Calculus For Spanning Administrative Domains, Jon Howell, David Kotz
An Access-Control Calculus For Spanning Administrative Domains, Jon Howell, David Kotz
Computer Science Technical Reports
In our quest to give users uniform access to resources unimpeded by administrative boundaries, we discovered that we needed transitive sharing among users, with the possibility of restricted access along each sharing link. To achieve that goal, we extend Lampson et al.'s calculus for access control to support restricted delegations. We discuss the advantages of our extension, including the simplification of constructs like ACLs and statement expiration. We also apply our extension to model the Simple Public Key Infrastructure and make suggestions about its future development. Our extended calculus exposes some surprising consequences in such systems that use restricted delegation.
Sar By Ms For Functional Genomics (Structure-Activity Relation By Mass Spectrometry), Bruce Randall Donald, Chris Bailey-Kellogg, John J. Kelley Iii, Cliff Stein
Sar By Ms For Functional Genomics (Structure-Activity Relation By Mass Spectrometry), Bruce Randall Donald, Chris Bailey-Kellogg, John J. Kelley Iii, Cliff Stein
Computer Science Technical Reports
Large-scale functional genomics will require fast, high-throughput experimental techniques, coupled with sophisticated computer algorithms for data analysis and experiment planning. In this paper, we introduce a combined experimental-computational protocol called Structure-Activity Relation by Mass Spectrometry (SAR by MS), which can be used to elucidate the function of protein-DNA or protein-protein complexes. We present algorithms for SAR by MS and analyze their complexity. Carefully-designed Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI TOF) and Electrospray Ionization (ESI) assays require only femtomolar samples, take only microseconds per spectrum to record, enjoy a resolution of up to one dalton in $10^6$, and (in the case of …
A Game-Theoretic Formulation Of Multi-Agent Resource Allocation, Jonathan Bredin, Rajiv T. Maheswaran, Cagri Imer, Tamer Basar, David Kotz, Daniela Rus
A Game-Theoretic Formulation Of Multi-Agent Resource Allocation, Jonathan Bredin, Rajiv T. Maheswaran, Cagri Imer, Tamer Basar, David Kotz, Daniela Rus
Computer Science Technical Reports
This paper considers resource allocation in a network with mobile agents competing for computational priority. We formulate this problem as a multi-agent game with the players being agents purchasing service from a common server. We show that there exists a computable Nash equilibrium when agents have perfect information into the future. We simulate a network of hosts and agents using our strategy to show that our resource-allocation mechanism effectively prioritizes agents according to their endowments.
An Environment For The Facilitation Of Robotic Programming, Artem Lifschitz
An Environment For The Facilitation Of Robotic Programming, Artem Lifschitz
Computer Science Technical Reports
I have developed, tested, and evaluated a robot programming environment organized as a library of flexible data structures to facilitate the creation of robotics programs. Abstractions are the basis of all of the achievements of Computer Science, and if it were possible to create a truly flexible, generic abstraction for the programming of robots -- the science of robotics could advance at a faster pace. For this reason, I have attempted to implement the abstraction of low-level commands, and the assembling of them into hierarchies of higher-level actions. My libraries provide mechanisms for the manipulation and queuing of actions, as …
Mobile-Agent Planning In A Market-Oriented Environment, Jonathan Bredin, David Kotz, Daniela Rus
Mobile-Agent Planning In A Market-Oriented Environment, Jonathan Bredin, David Kotz, Daniela Rus
Computer Science Technical Reports
We propose a method for increasing incentives for sites to host arbitrary mobile agents in which mobile agents purchase their computing needs from host sites. We present a scalable market-based CPU allocation policy and an on-line algorithm that plans a mobile agent's expenditure over a multihop ordered itinerary. The algorithm chooses a set of sites at which to execute and computational priorities at each site to minimize execution time while preserving a prespecified budget constraint. We present simulation results of our algorithm to show that our allocation policy and planning algorithm scale well as more agents are added to the …
Using Haptic Vector Fields For Animation Motion Control, Bruce Randall Donald, Frederick Henle
Using Haptic Vector Fields For Animation Motion Control, Bruce Randall Donald, Frederick Henle
Computer Science Technical Reports
We are exploring techniques for animation authoring and editing using a haptic force-feedback device. In our system, a family of animations is encoded by a bundle of trajectories. This bundle in turn defines a time-varying, higher-order vector field on a configuration space for the animation. A haptic input device provides a low-dimensional parameterization of the resulting dynamical system, and the haptic force feedback permits browsing and editing of the space of animations, by allowing the user to experience the vector field as physical forces.
Greedy Approximation Algorithms For K-Medians By Randomized Rounding, Neal E. Young
Greedy Approximation Algorithms For K-Medians By Randomized Rounding, Neal E. Young
Computer Science Technical Reports
We give an improved approximation algorithm for the general k-medians problem. Given any \epsilon>0, the algorithm finds a solution of total distance at most D(1+\epsilon) using at most k ln(n+n/\epsilon) medians (a.k.a. sites), provided some solution of total distance D using k medians exists. This improves over the best previous bound (w.r.t. the number of medians) by a factor of \Omega(1/\epsilon) provided 1/\epsilon=n^O(1). The algorithm is a greedy algorithm, derived using the method of oblivious randomized rounding. It requires at most k ln(n+n/\epsilon) linear-time iterations. We also derive algorithms for fractional and weighted variants of the problem.