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22nd Annual Symposium on Foundations of Computer Science (sfcs 1981)

28-30 Oct. 1981

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Displaying Results 1 - 25 of 55
  • [Front cover]

    Publication Year: 1981, Page(s): C1
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    Freely Available from IEEE
  • Table of contents

    Publication Year: 1981, Page(s):vii - ix
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    Freely Available from IEEE
  • Foreword

    Publication Year: 1981, Page(s): iii
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    Freely Available from IEEE
  • New lower bound techniques for VLSI

    Publication Year: 1981, Page(s):1 - 12
    Cited by:  Papers (40)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1620 KB)

    In this paper, we use crossing number and wire area arguments to find lower bounds on the layout area and maximum edge length of a variety of computationally useful networks. In particular, we describe 1) an N-node planar graph which has layout area Θ(NlogN), and maximum edge length Θ(N1/2/log1/2N), 2) an N-node graph with an O(N1/2)-separator which has layout area Θ(Nlog2N) a... View full abstract»

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  • Census functions: An approach to VLSI upper bounds

    Publication Year: 1981, Page(s):13 - 22
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1226 KB)

    A model of VLSI computation suitable for the description of algorithms at a high level is introduced. The model is basically a language to express parallel computations which can be efficiently implemented by a VLSI circuit. This language is used to describe area-time efficient algorithms for a few well known graph problems. The exact complexity of these algorithms and their relevance to recent wo... View full abstract»

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  • Optimizing synchronous systems

    Publication Year: 1981, Page(s):23 - 36
    Cited by:  Papers (180)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1972 KB)

    The complexity of integrated-circuit chips produced today makes it feasible to build inexpensive, special-purpose subsystems that rapidly solve sophisticated problems on behalf of a general-purpose host computer. This paper contributes to the design methodology of efficient VLSI algorithms. We present a transformation that converts synchronous systems into more time-efficient, systolic implementat... View full abstract»

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  • On relations between input and communication/computation in VLSI

    Publication Year: 1981, Page(s):37 - 44
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (741 KB)

    First Page of the Article
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  • Two-way counter machines and Diophantine equations

    Publication Year: 1981, Page(s):45 - 52
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (812 KB)

    Let Q be the class of deterministic two-way one-counter machines accepting only bounded languages. Each machine in Q has the property that in every accepting computation, the counter makes at most a fixed number of reversals. We show that the emptiness problem for Q is decidable. When the counter is unrestricted or when the machine is provided with two reversal-bounded counters, the emptiness prob... View full abstract»

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  • A time-space tradeoff for language recongnition

    Publication Year: 1981, Page(s):53 - 57
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (702 KB)

    We define a language L and show that its time and space complexities T and S must satisfy T2S ≥ cn3 even allowing machines with multiple (non random) access to the input. View full abstract»

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  • Simulations among multidimensional turing machines

    Publication Year: 1981, Page(s):58 - 67
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1303 KB)

    For all d ≥ 1 and all e ≫ d, every deterministic multihead e-dimensional Turing machine of time complexity T(n) can be simulated on-line by a deterministic multihead d-dimensional Turing machine in time O(T(n)1+1/d-1/e(log T(n))O(1)). This simulation almost achieves the known lower bound Ω(T(n)1+1/d-1/e) on the time required. Furthermore, there is a deterministic d-dimensiona... View full abstract»

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  • On heads versus tapes

    Publication Year: 1981, Page(s):68 - 73
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (617 KB)

    2-dimensional 2-tape Turing machines cannot simulate 2-dimensional Turing machines with 2 heads on 1 tape in real time. View full abstract»

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  • On the equivalence and containment problems for unambiguous regular expressions, grammars, and automata

    Publication Year: 1981, Page(s):74 - 81
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1102 KB)

    The known proofs that the equivalence and containment problems for the regular and for the linear context-free grammars are PSPACE-complete and undecidable, respecitvely, depend upon consideration of ambiguous grammars. We prove that this dependence is inherent. Deterministic polynomial time algorithms are presented for; (1) the equivalence and containment problems for the unambiguous regular gram... View full abstract»

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  • On the asymptotic complexity of matrix multiplication

    Publication Year: 1981, Page(s):82 - 90
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (905 KB)

    The main results of this paper have the following flavor: given one algorithm for multiplying matrices, there exists another, better, algorithm. A consequence of these results is that ω, the exponent for matrix multiplication, is a limit point, that is, cannot be realized by any single algorithm. We also use these results to construct a new algorithm which shows that ω ≪ 2.495... View full abstract»

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  • On the direct sum conjecture

    Publication Year: 1981, Page(s):91 - 94
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    First Page of the Article
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  • Computation of algebraic functions with root extractions

    Publication Year: 1981, Page(s):95 - 100
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (733 KB)

    We consider the problem of computing a set of algebraic functions that involve extracting roots of various degrees. We show that the complexity of computing a large class of algebraic functions is determined by the Galois group G of the extension generated by the functions. We relate the minimum cost to decomposing G into a sequence of normal subgroups such that each factor group is cyclic. We der... View full abstract»

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  • An O(N4/3) lower bound on the mono tone network complexity of N-TH degree convolution

    Publication Year: 1981, Page(s):101 - 108
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (609 KB)

    We prove an Ω(n4/3) lower bound for the number of ∧-gates in any monotone network computing n-th degree convolution. View full abstract»

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  • Non-existence of one-dimensional expanding graphs

    Publication Year: 1981, Page(s):109 - 114
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (740 KB)

    Expanding graphs are the basic building blocks used in constructions of graphs with special connectivity properties such as superconcentrators. The only known explicit method (Margulis[7], Gabber and Galil[5]) of constructing arbitrarily large expanding graphs with a linear number of edges, uses graphs whose edges are defined by a finite set of linear mappings restricted to a two-dimensional set, ... View full abstract»

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  • A minimum spanning ellipse algorithm

    Publication Year: 1981, Page(s):115 - 122
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (795 KB)

    An algorithm to find the minimum spanning ellipse of a convex set of points in the plane, i.e., the ellipse of minimum area containing the set, is described. The result for higher dimensions is suggested, along with a brief discussion of possible applications. View full abstract»

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  • A direct dynamic solution to range search and related problems for product regions

    Publication Year: 1981, Page(s):123 - 126
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (484 KB)

    A simple property of number representations yields a unit cross section relation between points and interval representations. Applied to product regions in a vector space, one obtains simple, practical and flexible algorithms for dynamic range search and related queries. View full abstract»

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  • Deletion algorithms for hashing that preserve randomness

    Publication Year: 1981, Page(s):127 - 132
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (794 KB)

    This paper studies the problem of finding efficient deletion algorithms for the coalesced hashing method, in which a portion of memory (called the address region) serves as the range of the hash function while the rest of memory (called the cellar) is devoted solely to storing records that collide when inserted. We present a deletion algorithm, which solves the open problem described in [Knu73, &#... View full abstract»

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  • Implicit data structures for the weighted dictionary problem

    Publication Year: 1981, Page(s):133 - 139
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (924 KB)

    Several new data structures are presented for dictionaries containing elements with different weights (access probabilities). The structures use just one location in addition to those required for the values of the elements, and support access times that are within a constant multiplicative factor of optimal, in terms of the rank of the weight of the desired element. Self-organizing heuristics are... View full abstract»

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  • Possible futures, acceptances, refusals, and communicating processes

    Publication Year: 1981, Page(s):140 - 149
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1185 KB)

    Two distinct models for the notion of communicating processes are introduced, developed and related. The first, called the possible-futures model, is a generalization to nondeterministic systems of the familiar derivative (Nerode equivalence class) construction. The second, called the acceptance-refusals model, is a slight strengthening of a model introduced by Hoare, Brookes, and Roscoe. The PF m... View full abstract»

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  • Symmetry breaking in distributive networks

    Publication Year: 1981, Page(s):150 - 158
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1105 KB)

    Given a ring (cycle) of n processes it is required to design the processes so that they will be able to choose a leader (a uniquely designated process) by sending messages along the ring. If the processes are indistiguishable there is no deterministic algorithm, and therefore probabilistic algorithms are proposed. These algorithms need not terminate, but their expected complexity (time or number o... View full abstract»

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  • Unanimity in an unknown and unreliable environment

    Publication Year: 1981, Page(s):159 - 168
    Cited by:  Papers (5)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1222 KB)

    Can unanimity be achieved in an unknown and unreliable distributed system? We analyze two extreme models of networks: one in which all the routes of communication are known, and the other in which not even the topology of the network is known. We prove that independently of the model, unanimity is achievable if and only if the number of faulty processors in the system is 1. less than one half of t... View full abstract»

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  • Symmetry in systems of asynchronous processes

    Publication Year: 1981, Page(s):169 - 174
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (840 KB)

    A new solution to the problem of deadlock-free mutual exclusion of N processes is given which uses less shared space than earlier solutions (one variable which may take on N values and N binary variables). The solution uses only indivisible reads and writes of shared variables for communication and is symmetric among the processes. Two definitions of symmetry are developed. The strong definition o... View full abstract»

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