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26th Annual Symposium on Foundations of Computer Science (sfcs 1985)

21-23 Oct. 1985

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Displaying Results 1 - 25 of 66
  • [Front cover]

    Publication Year: 1985, Page(s): C1
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    Freely Available from IEEE
  • Table of contents

    Publication Year: 1985, Page(s):ix - xii
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  • Foreword

    Publication Year: 1985, Page(s): iii
    Cited by:  Papers (2)
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  • Machtey Award

    Publication Year: 1985, Page(s): v
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  • Separating the polynomial-time hierarchy by oracles

    Publication Year: 1985, Page(s):1 - 10
    Cited by:  Papers (70)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1248 KB)

    We present exponential lower bounds on the size of depth-k Boolean circuits for computing certain functions. These results imply that there exists an oracle set A such that, relative to A, all the levels in the polynomial-time hierarchy are distinct, i.e., ΣkP,A is properly contained in Σk+1P,A for all k. View full abstract»

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  • Deterministic simulation of probabilistic constant depth circuits

    Publication Year: 1985, Page(s):11 - 19
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (845 KB)

    We explicitly construct, for every integer n and ε ≫ 0, a family of functions (psuedo-random bit generators) fn,ε:{0,1}nε → {0,1}n with the following property: for a random seed, the pseudorandom output "looks random" to any polynomial size, constant depth, unbounded fan-in circuit. Moreover, the functions fn,ε themselves can be computed by uniform polyno... View full abstract»

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  • Amplification of probabilistic boolean formulas

    Publication Year: 1985, Page(s):20 - 29
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1030 KB)

    The amplification of probabilistic Boolean formulas refers to combining independent copies of such formulas to reduce the error probability. Les Valiant used the amplification method to produce monotone Boolean formulas of size O(n5.3) for the majority function of n variables. In this paper we show that the amount of amplification that Valiant obtained is optimal. In addition, using the amplificat... View full abstract»

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  • On networks of noisy gates

    Publication Year: 1985, Page(s):30 - 38
    Cited by:  Papers (49)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (810 KB)

    We show that many Boolean functions (including, in a certain sense, "almost all" Boolean functions) have the property that the number of noisy gates needed to compute them differs from the number of noiseless gates by at most a constant factor. This may be contrasted with results of von Neumann, Dobrushin and Ortyukov to the effect that (1) for every Boolean function, the number of noisy gates nee... View full abstract»

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  • How easy is local search?

    Publication Year: 1985, Page(s):39 - 42
    Cited by:  Papers (6)
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    First Page of the Article
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  • Identification is easier than decoding

    Publication Year: 1985, Page(s):43 - 50
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (578 KB)

    Several questions related to the complexity of communication over channels with noise are addressed. We compare some of our results to wellknown results in information theory. In particular we compare the following two problems. Assuming that the communication channel between two processors P1 and P2 makes an error with probability ε≫0, the identification problem is to determine whet... View full abstract»

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  • Three theorems on polynomial degrees of NP-sets

    Publication Year: 1985, Page(s):51 - 55
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (681 KB)

    We show that recursive ascending sequences of polynomial time (p-) degrees do not possess minimal upper bounds; that, for every nonzero p-degree a, there is a lesser nonzero p-degree b which does not help a; and that every nonzero p-degree is half of a minimal pair. View full abstract»

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  • Simulating two pushdown stores by one tape in O(n1.5v) time

    Publication Year: 1985, Page(s):56 - 64
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1080 KB)

    Based on two graph separator theorems, we present two unexpected upper bounds and resolve several open problems for on-line computations. (1) 1 tape nondeterministic machines can simulate 2 pushdown stores in time O(n1.5√logn) (true for both on-line and off-line machines). Together with the Ω(n1.5/√logn) lower bound, this solves the open problem 1 in [DGPR] for the 1 tape vs... View full abstract»

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  • Nondeterministic versus probabilistic linear search algorithms

    Publication Year: 1985, Page(s):65 - 73
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (953 KB)

    The "component counting lower bound" known for deterministic linear search algorithms (LSA's) also holds for their probabilistic versions (PLSA's) for many problems, even if two-sided error is allowed, and if one does not charge for probabilistic choice. This implies lower bounds on PLSA's for e.g. the element distinctness problem (n log n) or the knapsack problem (n2). These results yield the fir... View full abstract»

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  • The complexity of facets resolved

    Publication Year: 1985, Page(s):74 - 78
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (588 KB)

    First Page of the Article
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  • Using dual approximation algorithms for scheduling problems: Theoretical and practical results

    Publication Year: 1985, Page(s):79 - 89
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    The problem of scheduling a set of n jobs on m identical machines so as to minimize the makespan time is perhaps the most well-studied problem in the theory of approximation algorithms for NP-hard optimization problems. In this paper we present the strongest possible type of result for this problem, a polynomial approximation scheme. More precisely, for each ε, we give an algorithm that run... View full abstract»

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  • A scaling algorithm for weighted matching on general graphs

    Publication Year: 1985, Page(s):90 - 100
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1692 KB)

    This paper presents an algorithm for maximum matching on general graphs with integral edge weights, running in time O(n3/4m lg N), where n, m and N are the number of vertices, number of edges, and largest edge weight magnitude, respectively. The best previous bound is O(n(mlg lg lgd n + n lg n)) where d is the density of the graph. The algorithm finds augmenting paths in batches by scaling the wei... View full abstract»

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  • An all pairs shortest path algorithm with expected running time O(n 2logn)

    Publication Year: 1985, Page(s):101 - 105
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (640 KB)

    An algorithm is described that solves the all pairs shortest path problem for a nonnegatively weighted graph. The algorithm has an average requirement on quite general classes of random graphs of O(n2logn) time, where n is the number of vertices in the graph. View full abstract»

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  • Recognizing circle graphs in polynomial time

    Publication Year: 1985, Page(s):106 - 116
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1234 KB)

    Our main result is a polynomialtime algorithm for deciding whether a given graph is a circle graph, that is, the intersection graph of a set of chords on a circle. Our algorithm utilizes two new graph-theoretic results, regarding necessary induced subgraphs of graphs having neither articulation points nor similar pairs of vertices. View full abstract»

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  • Why certain subgraph computations requite only linear time

    Publication Year: 1985, Page(s):117 - 125
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1033 KB)

    A general problem in computational graph theory is that of finding an optimal subgraph H of a given weighted graph G. The matching problem (which is easy) and the traveling salesman problem (which is not) are well known examples of this general problem. In the literature one can also find a variety of ad hoc algorithms for solving certain special cases in linear time. We present a general methodol... View full abstract»

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  • Efficient string matching in the presence of errors

    Publication Year: 1985, Page(s):126 - 136
    Cited by:  Papers (5)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1579 KB)

    Consider the string matching problem where differences between characters of the pattern and characters of the text are allowed. Each difference is due to either a mismatch between a character of the text and a character of the pattern or a superfluous character in the text or a superfluous character in the pattern. Given a text of length n, a pattern of length m and an integer k, we present an al... View full abstract»

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  • The least weight subsequence problem

    Publication Year: 1985, Page(s):137 - 143
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (795 KB)

    The least weight subsequence (LWS) problem is introduced, and is shown to be equivalent to the classic minimum path problem for directed graphs. A special case of the LWS problem is shown to be solvable in O(n log n) time generally and, for certain weight functions, in linear time. A number of applications are given, including an optimum paragraph formation problem and the problem of finding a min... View full abstract»

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  • Motion planning in the presence of moving obstacles

    Publication Year: 1985, Page(s):144 - 154
    Cited by:  Papers (94)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1582 KB)

    This paper investigates the computational complexity of planning the motion of a body B in 2-D or 3-D space, so as to avoid collision with moving obstacles of known, easily computed, trajectories. Dynamic movement problems are of fundamental importance to robotics, but their computational complexity has not previously been investigated. We provide evidence that the 3-D dynamic movement problem is ... View full abstract»

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  • Visibility-polygon search and euclidean shortest paths

    Publication Year: 1985, Page(s):155 - 164
    Cited by:  Papers (20)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1305 KB)

    Consider a collection of disjoint polygons in the plane containing a total of n edges. We show how to build, in O(n2) time and space, a data structure from which in O(n) time we can compute the visibility polygon of a given point with respect to the polygon collection. As an application of this structure, the visibility graph of the given polygons can be constructed in O(n2) time and space. This i... View full abstract»

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  • Slimming down search structures: A functional approach to algorithm design

    Publication Year: 1985, Page(s):165 - 174
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1257 KB)

    We establish new upper bounds on the complexity of several "rectangle" problems. Our results include, for instance, optimal algorithms for range counting and rectangle searching in two dimensions. These involve linear space implementations of range trees and segment trees. The algorithms we give are simple and practical; they can be dynamized and taken into higher dimensions. Also of interest is t... View full abstract»

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  • The complexity of recognizing polyhedral scenes

    Publication Year: 1985, Page(s):175 - 185
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (979 KB)

    Given a drawing of straight lines on the plane, we wish to decide whether it is the projection of the visible part of a set of opaque polyhedra. Although there is an extensive literature and reports on empirically succesful algorithm: for this problem, there has been no definite result concerning its complexity. In this paper we show that, rather surprisingly, this problem is NP-complete. This is ... View full abstract»

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