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The 2004 Benjamin Franklin Medal in Computer and Cognitive Science presented to Richard M. Karp

JOURNAL OF THE FRANKLIN INSTITUTE-ENGINEERING AND APPLIED MATHEMATICS 2005年第6期342卷 629-637页

作者： Char, B Drexel Univ Dept Comp Sci Philadelphia PA 19104 USA

The Benjamin Franklin Medal in Computer and Cognitive Science is awarded to Dr. Richard M. Karp for his contributions to the understanding of computational complexity. His work helps programmers find workable solution procedures avoiding approaches that would fail to find a solution in a reasonable amount of time. Scientific, commercial, or industrial situations where his work applies include establishing least-cost schedules for industrial production, transportation routing, circuit layout, communication network design, and predicting the spatial structure of a protein from its amino acid sequencing. (c) 2005 Published by Elsevier Ltd. on behalf of The Franklin Institute.

关键词： computational complexity polynomial time algorithms theory of computation NP-completeness combinatorial problems

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Establishment of survivable connections in WDM networks using partial path protection

Establishment of survivable connections in WDM networks usin...

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IEEE International Conference on Communications (ICC 2005)

作者： Xue, G Zhang, W Tang, J Thulasiraman, K Arizona State Univ Dept Comp Sci & Engn Tempe AZ 85287 USA

ISBN: (纸本)0780389387

As a generalization of the traditional path protection scheme in WDM networks where a backup path is needed for each active path, the partial path protection scheme uses a collection of backup paths to protect an active path, where each backup path in the collection protects one or more links on the active path such that every link on the active path is protected by one of the backup paths. While there is no known polynomial time algorithm for computing an active path and a corresponding backup path using the path protection scheme for a given source-destination node pair, we show that an active path and a corresponding collection of backup paths using the partial path protection scheme can be computed in polynomial time, whenever they exist, under each of the following two network models: (a) dedicated protection in WDM networks without wavelength converters;and (b) shared protection in WDM networks without wavelength converters. Under each of the two models, we prove that for any given source s and destination d in the network, if one candidate active path connecting s and d is protectable using partial path protection, then any candidate active path connecting s and d is also protectable using partial path protection. This fundamental property leads to efficient shortest active path algorithms that can find an active path and its corresponding partial path protections whenever they exist. Simulation results show that shared partial path protection outperforms shared path protection in terms of blocking probability.

关键词： WDM networks backup multiplexing partial path protection polynomial time algorithms

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List partitions

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SIAM JOURNAL ON DISCRETE MATHEMATICS 2003年第3期16卷 449-478页

作者： Feder, T Hell, P Klein, S Motwani, R Simon Fraser Univ Sch Comp Sci Burnaby BC V5A 1S6 Canada Univ Fed Rio de Janeiro Dept Ciencia Comp IM COPPE Sistemas BR-21945970 Rio De Janeiro Brazil Stanford Univ Dept Comp Sci Stanford CA 94305 USA

List partitions generalize list colorings and list homomorphisms. (We argue that they may be called list "semihomomorphisms.") Each symmetric matrix M over 0, 1, (*) defines a list partition problem. Different choices of the matrix M lead to many well-known graph theoretic problems, often related to graph perfection, including the problem of recognizing split graphs, finding homogeneous sets, clique cutsets, stable cutsets, and so on. The recent proof of the strong perfect graph theorem employs three kinds of decompositions that can be viewed as list partitions. We develop tools which allow us to classify the complexity of many list partition problems and, in particular, yield the complete classification for small matrices M. Along the way, we obtain a variety of specific results, including generalizations of Lovasz's communication bound on the number of clique-versus-stable-set separators, polynomial time algorithms to recognize generalized split graphs, a polynomial algorithm for the list version of the clique cutset problem, and the first subexponential algorithm for the skew cutset problem of Chvatal. We also show that the dichotomy (NP-complete versus polynomial time solvable), conjectured for certain graph homomorphism problems, would, if true, imply a slightly weaker dichotomy (NP-complete versus quasi-polynomial) for our list partition problems.

关键词： list homomorphisms H-colorings graph partitions perfect graphs split graphs skew cutsets clique cutsets 2-joins communication bound dichotomy constraint satisfaction problems quasi-polynomial algorithms NP-completeness polynomial time algorithms

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A 2-approximation algorithm 2-ABIS for 2-vertex- connectivity augmentation of specified vertices in a graph

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2003年第4期E86A卷 822-828页

作者： Tamura, M Taoka, S Watanabe, T Hiroshima Univ Grad Sch Engn Higashihiroshima 7398527 Japan

The 2-vertex-connectivity augmentation problem for specified vertices (2VCA-SV) is defined as follows: Given an undirected graph G = (V, E), a subgraph G(0) = (V, E') of G, a specified set of vertices S C V and a weight function w : E --> R+ (nonnegative real numbers), find a set E" subset of or equal to E - E' with the minimum total weight, such that G(0) + E" (V, E' boolean OR E") has at least two internally disjoint paths between any pair of vertices in S. In this paper, we propose an O(\Vparallel toE\ + \V\(2) log \V\) time algorithm 2-ABIS, whose performance ratio is 2 (3, respectively), for 2VCA-SV if G(0) has a connected component containing S (otherwise).

关键词： graphs augmentation problems vertex-connectivity performance ratios polynomial time algorithms

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Optimal multichannel data transmission in computer networks

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COMPUTER COMMUNICATIONS 2003年第7期26卷 759-765页

作者： Xue, GL Arizona State Univ Dept Comp Sci & Engn Tempe AZ 85287 USA

We study end-to-end routing in a communication system where there is a bandwidth and a propagation delay associated with each link, as well as a queuing delay associated with each intermediate node. We present a polynomial time algorithm for computing an optimal multichannel routing to transmit a given message. Examples are also given to show that several previously published path-based algorithms for this problem are suboptimal. We then generalize the multichannel routing problem to delay-constrained multichannel routing problem and show that this generalized problem can also be solved in polynomial time. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： communication systems computer communications end-to-end delay multichannel routing polynomial time algorithms quality of service

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Antidirected hamiltonian paths between specified vertices of a tournament

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DISCRETE APPLIED MATHEMATICS 2002年第1-3期117卷 87-98页

作者： Hell, P Rosenfeld, M Simon Fraser Univ Sch Comp Sci Dept Comp Sci Burnaby BC V5A 1S6 Canada Univ Washington Comp & Software Syst Program Tacoma WA 98402 USA

We prove that in any tournament there is an antidirected hamiltonian path from a specified first vertex to a specified last vertex, and starting with an arc of specified direction, as long as both the first vertex and the last vertex satisfy an obvious minimally necessary condition. We apply this result to give a polynomial time algorithm to find an antidirected hamiltonian path between two specified vertices of an input tournament. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： tournaments hamiltonian paths antidirected paths polynomial time algorithms

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Cyclic scheduling in a robotic production line

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JOURNAL OF SCHEDULING 2002年第1期5卷 23-41页

作者： Kats, V Levner, E Holon Inst Technol Dept Comp Sci IL-58102 Holon Israel Technion Israel Inst Technol Fac Ind Engn & Management IL-32000 Haifa Israel

The solution of cyclic scheduling problems is part of the classical repertoire on scheduling algorithms. We consider a problem of cyclic scheduling of identical parts in a production line where transportation of the parts between machines is performed by several robots. The problem is to find co-ordinated movements of the parts and robots in the line with the no-wait constraints imported;the objective is to maximize the throughput rate. Unlike many previous algorithms which are either heuristic or at best solve the single-robot version of the problem in O(m(4) log m) time, the proposed algorithm provides an exact solution for the more complicated case of multiple robots and solves the problem in O(m(3) log m) time, where in denotes the number of machines in the line. Copyright (C) 2002 John Wiley Sons, Ltd.

关键词： subject classification deterministic scheduling cyclic scheduling robotic scheduling polynomial time algorithms

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Graph connectivity and its augmentation: applications of MA orderings

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DISCRETE APPLIED MATHEMATICS 2002年第1-3期123卷 447-472页

作者： Nagamochi, H Ibaraki, T Toyohashi Univ Technol Dept Informat & Comp Sci Tenpa Ku Toyohashi Aichi 4418580 Japan Kyoto Univ Dept Appl Math & Phys Sakyo Ku Kyoto 6068501 Japan

This paper surveys how the maximum adjacency (MA) ordering of the vertices in a graph can be used to solve various graph problems. We first explain that the minimum cut problem can be solved efficiently by utilizing the MA ordering. The idea is then extended to a fundamental operation of a graph, edge splitting. Based on this, the edge-connectivity augmentation problem for a given k (and also for the entire range of k) can be solved efficiently by making use of the MA ordering, where it is asked to add the smallest number of new edges to a given graph so that its edge-connectivity is increased to k. Other related topics are also surveyed. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： graphs MA ordering minimum cuts edge-connectivity graph augmentation polynomial time algorithms

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Symbolic pointer analysis 02

Symbolic pointer analysis

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International Conference on Computer-Aided Design

作者： Zhu, JW Univ Toronto Dept Elect & Comp Engn Toronto ON M5S 3G4 Canada

ISBN: (纸本)0780376072

One of the bottlenecks in the recent movement of hardware synthesis from behavioral C programs is the difficulty in reasoning about runtime pointer values at compile time. The pointer analysis problem has been investigated in the compiler community for two decades, which has yielded efficient, polynomial time algorithms for context-insensitive analysis. However, at the accuracy level for which hardware synthesis is desired, namely context and flow sensitive analysis, the time and space complexity of the best algorithms reported grow exponentially with program size. In this paper, we present our first step towards a new analysis technology which potentially leads to almost-linear time complexity and sub-linear space complexity algorithm even for the most accurate analysis. The key idea that contributes to this efficiency is to implicitly encode the pointer-to relation in the Boolean domain, thereby capturing the procedure transfer function completely, compactly and canonically. This represents a wide departure from the traditional techniques, all of which explicitly capture pointer-to relation using variations of point-to graph, which have to be re-evaluated for different calling contexts. Experiments for our first flow-insensitive algorithm on common benchmarks show promising result.

关键词： hardware-software codesign integrated circuit design circuit CAD computational complexity Boolean functions program compilers symbolic pointer analysis hardware synthesis behavioral C programs runtime pointer values compile time polynomial time algorithms context-insensitive analysis context sensitive analysis flow sensitive analysis almost-linear time complexity sub-linear space complexity algorithm Boolean domain pointer-to relation encoding procedure transfer function point-to graph variations calling contexts flow-insensitive algorithm

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A distributed algorithm of efficient core discipline on weighted bipartite networks

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COMPUTER SYSTEMS SCIENCE AND ENGINEERING 2002年第1期17卷 13-22页

作者： Yang, SJ Soochow Univ Dept Comp & Informat Sci Taipei Taiwan

A core of a network is the path that selects one efficient link from all given measured paths. Thus, finding the efficient core is the key issue to a bipartite network. in this paper, we propose the distributed algorithms for solving the hybrid cost core using Min-Max and Min-Average distance measures on weighted bipartite networks. The required tasks are to allocate a set of servers on some nodes that can form a core, and to provide the services that clients need in a bipartite network BN(V, E). First, essential strategies for MMDC and MADC on general networks are presented and the models of bipartite networks are described. Then, Test-MMDC and Test-MADC procedures are further analyzed and illustrated for general and special types on weighted bipartite networks, respectively. Based on that analysis, MADC problem is NP-hard on some general cases of weighted bipartite networks. For special types, we propose the polynomial time algorithms for solving the hybrid cost core under two different distance measures. Meanwhile, applying these approaches to extended beta-cores of bipartite networks are also discussed, where betagreater than or equal to2 and beta CE Z(+). Consequently, the final results which are derived by this model's technique can be solved in polynomial time with an e factor, where e is the number of possible combinations in the case of beta-cores on weighted bipartite networks.

关键词： hybrid cost core polynomial time algorithms bipartite networks Min-Max Distance Cores Min-Average Distance Cores

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