Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing最新文献_第2页

Self-routing superconcentrators Self-routing superconcentrators

Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing Pub Date : 1993-06-01 DOI: 10.1145/167088.167195

N. Pippenger

{"title":"Self-routing superconcentrators","authors":"N. Pippenger","doi":"10.1145/167088.167195","DOIUrl":"https://doi.org/10.1145/167088.167195","url":null,"abstract":"Superconcentrators are switching systems that solve the generic problem of interconnecting clients and servers during sessions, in situations where either the clients or the servers are interchangeable ( so that it does not matter which client is connected to which server). Previous constructions of superconcentrators have required an external agent to find the interconnections appropriate in each instance. We remedy this shortcoming by constructing superconcentrators that are self'outing, in the sense that they compute for themselves the required interconnections. Specifically, we show how to construct, for each n, a system S n with the following properties : (1) The system S n has n inputs, n outputs, and O(n) components, each of which is one of a fixed finite number of finite automata and is connected to a fixed finite number of other components through cables, each of which carries signals from a fixed finite alphabet. (2 ) When some of the inputs, and an equal number of outputs, are marked ( by the presentation of a certain signal) then after O(log n) steps (a time proportional to the diameter of the network ) the system will establish a set of disjoint paths from the marked inputs to the marked outputs. The size O(n) is of course optimal for superconcentrators, as is the diameter O(log n) for superconcentrators of bounded degree.","PeriodicalId":280602,"journal":{"name":"Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133732095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 44

The network inhibition problem 网络抑制问题

Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing Pub Date : 1993-06-01 DOI: 10.1145/167088.167286

C. Phillips

引用次数: 253

A theory of parameterized pattern matching: algorithms and applications 参数化模式匹配理论:算法与应用

Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing Pub Date : 1993-06-01 DOI: 10.1145/167088.167115

B. S. Baker

{"title":"A theory of parameterized pattern matching: algorithms and applications","authors":"B. S. Baker","doi":"10.1145/167088.167115","DOIUrl":"https://doi.org/10.1145/167088.167115","url":null,"abstract":"This paper develops a theory and algoritbrns for an application problem arising in software maintenance. The application is to track down duplication in a large software system. We want to find not only exact matches between sections of code, but parametrized matches, where a parametrized match between two sections of code means that one section can be transformed into the other by replacing the parameter names (e.g. identifiers and constants) of one section by the parameter names of the other via a one-to-one function. This paper formalizes this problem in terms of parametrized strings and parametrized pattern matching and detirtes a new data structure (parametrized sujjfi.x tree) suitable for parametrized pattern matching. It gives efficient algorithms for constructing this data structure, efficient algorithms for parametrized pattern matchmg, and an efficient algorithm for timing all maximal parametrized matches over a threshold length in a parametrized string. The algorithms for constructing parametrized suffix trees and for reporting duplication over a threshold length have been implemented. Tests on C code indicate that these algorithms should perform well in the application.","PeriodicalId":280602,"journal":{"name":"Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114536791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 168

Linear programming without the matrix 没有矩阵的线性规划

Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing Pub Date : 1993-06-01 DOI: 10.1145/167088.167127

C. Papadimitriou, M. Yannakakis

{"title":"Linear programming without the matrix","authors":"C. Papadimitriou, M. Yannakakis","doi":"10.1145/167088.167127","DOIUrl":"https://doi.org/10.1145/167088.167127","url":null,"abstract":"We study the problem facing a set of decision-makers who must select values for the variables of a linear program, when only parts of the matrix are available to each of them. The goal is to find a feasible solution that is as close to the true optimum as possible, When each decision-maker decides one variable and knows all constraints involving this variable, we show that the worst-case ratio is related tc,the maximum number of variables appearing in each constraint, and a simple “safe” heuristic is optimal. Since this problem involves constrained optimization, there is a novel criterion, besides the competitive ratio, comparing the performance of a heuristic with the best feasible distributed algorithm, perhaps specializing on the current inst ante; we show different bounds for this parameter. When the constraint structure (the zero-nonzero pattern of the matrix) is known in advance, and the variables are partitioned bet ween decision-makers, then the optimum ratio is a complicated parameter of the associated hypergraph, which we bound from above and below in terms of variants of clique and graph coloring; but several interesting special cases are characterized completely. 1 Department of Computer Science and Engineering, University of California at San Diego. Research supported by the National Science Foundation. 2 AT&T Bell Laboratories, Murray Hill, NJ 07974. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fee arrd/or specific permission. 25th ACM STOC ‘93-51931CA, LE3A e 1993 ACM 0-89791-591-7/93/0005/0121 . ..$l .50","PeriodicalId":280602,"journal":{"name":"Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116126697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 114

Some complexity issues on the simply connected regions of the two-dimensional plane 二维平面单连通区域上的一些复杂性问题

Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing Pub Date : 1993-06-01 DOI: 10.1145/167088.167093

Arthur W. Chou, K. Ko

{"title":"Some complexity issues on the simply connected regions of the two-dimensional plane","authors":"Arthur W. Chou, K. Ko","doi":"10.1145/167088.167093","DOIUrl":"https://doi.org/10.1145/167088.167093","url":null,"abstract":"This paper studies the computational complexity of subsets of the plane R2. We propose a general framework in which continuous problems in computational complex analysis can be studied in the context of discrete complexity theory (i.e., the NP theory). This framework is based on the bit-operation model used in recursive analysis [Pour-El and Richards, 1989] and complexity theory of real functions of Ko and Friedman [1982]. It is an extension of the polynomial-time measure theory studied in Chapter 5 of Ko [1991]. The fundamental notion in this study is the class of bounded subsets of the plane R2 whose membership problem is polynomial-time solvable. We define two such notions: the polynomial-time approximable sets and the polynomial-time recognizable sets. Informally, a subset S ~ R2 is polynomial-time approzimable if there is a machine M which, on a given point z c R2 and an integer n, determines whether z is in S within time polynomial in n and admitting errors only on a set E ~ R2 of measure 2-”. A subset S ~ R2 is polynomial-time recognizable if there is a machine M which on a given point z G R2 and an integer n, determines whether z is in S within time polynomial in n and admitting errors only on points z that are within a distance 2-n of the boundary of S.3 To demonstrate that these two notions of polynomialtime computable sets are natural and interesting, we","PeriodicalId":280602,"journal":{"name":"Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121678576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 5

Quantum complexity theory 量子复杂性理论

Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing Pub Date : 1993-06-01 DOI: 10.1145/167088.167097

Ethan S. Bernstein, U. Vazirani

{"title":"Quantum complexity theory","authors":"Ethan S. Bernstein, U. Vazirani","doi":"10.1145/167088.167097","DOIUrl":"https://doi.org/10.1145/167088.167097","url":null,"abstract":"In this paper we study quantum computation from a complexity theoretic viewpoint. Our first result is the existence of an efficient universal quantum Turing machine in Deutsch's model of a quantum Turing machine (QTM) [Proc. Roy. Soc. London Ser. A, 400 (1985), pp. 97--117]. This construction is substantially more complicated than the corresponding construction for classical Turing machines (TMs); in fact, even simple primitives such as looping, branching, and composition are not straightforward in the context of quantum Turing machines. We establish how these familiar primitives can be implemented and introduce some new, purely quantum mechanical primitives, such as changing the computational basis and carrying out an arbitrary unitary transformation of polynomially bounded dimension. \u0000We also consider the precision to which the transition amplitudes of a quantum Turing machine need to be specified. We prove that $O(log T)$ bits of precision suffice to support a $T$ step computation. This justifies the claim that the quantum Turing machine model should be regarded as a discrete model of computation and not an analog one. \u0000We give the first formal evidence that quantum Turing machines violate the modern (complexity theoretic) formulation of the Church--Turing thesis. We show the existence of a problem, relative to an oracle, that can be solved in polynomial time on a quantum Turing machine, but requires superpolynomial time on a bounded-error probabilistic Turing machine, and thus not in the class $BPP$. The class $BQP$ of languages that are efficiently decidable (with small error-probability) on a quantum Turing machine satisfies $BPP subseteq BQP subseteq Ptime^{SP}$. Therefore, there is no possibility of giving a mathematical proof that quantum Turing machines are more powerful than classical probabilistic Turing machines (in the unrelativized setting) unless there is a major breakthrough in complexity theory.","PeriodicalId":280602,"journal":{"name":"Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125906064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1910

The asynchronous computability theorem for t-resilient tasks t弹性任务的异步可计算性定理

Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing Pub Date : 1993-06-01 DOI: 10.1145/167088.167125

M. Herlihy, N. Shavit

引用次数: 204

Short random walks on graphs 图上的短随机游走

Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing Pub Date : 1993-06-01 DOI: 10.1145/167088.167275

G. Barnes, U. Feige

引用次数: 73

Fast asynchronous Byzantine agreement with optimal resilience 具有最佳弹性的快速异步拜占庭协议

Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing Pub Date : 1993-06-01 DOI: 10.1145/167088.167105

R. Canetti, T. Rabin

引用次数: 313

Markov chains, computer proofs, and average-case analysis of best fit bin packing 马尔可夫链，计算机证明，和平均情况下最适合的装箱分析

Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing Pub Date : 1993-06-01 DOI: 10.1145/167088.167203

E. Coffman, David S. Johnson, P. Shor, R. Weber

{"title":"Markov chains, computer proofs, and average-case analysis of best fit bin packing","authors":"E. Coffman, David S. Johnson, P. Shor, R. Weber","doi":"10.1145/167088.167203","DOIUrl":"https://doi.org/10.1145/167088.167203","url":null,"abstract":"Many complex Coffrnan, Jr. 1, D. S. Johnsonl, P. W. Shorl, R. R. Weber2 pmcessea can be modeled by (countably) infinite, multidmens~onst Markov chains. Unfortunately, cnrnmt theoretical techniques for analyzing infinite Markov chains are for the most part limited to three or fewer dimensions. In this paper we propose a computer-aided approach to the analysis of higher-dimensional domains, using several open problems about the average-case behavior of the Best Fit bin packing algorithm as case studies. We show how to use dynamic and liiear programming to construct potential functions thal when applied to suitably modified multi-step versions of our original Markov chain, yield drifts that are bounded away fmm O. This enables us to completely classify the expected behavior of Best Fit under discrete uniform distributions U{J, K) when K is small. (Under U{ J, K}, the allowed item sizes are i/K, 1 S i S J, with all J possibilities equally likely.) In addition, we can answer yes to the long-standing open question of whether there exist distributions of thii form for which Best Fit yields linearly-growing waste. The proof of the latter theorem relies on a 24-hour computation, and although its validity does not depend on the linear programmingpackage we used, it does tely on the correctness of our dynamic progr smming code and of our computer’s implementation of the IEEE floating point standard.","PeriodicalId":280602,"journal":{"name":"Proceedings of the twenty-fifth annual ACM symposium on Theory of Computing","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134369611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 47