[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science

1-4 Oct. 1991

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  • Proceedings 32nd Annual Symposium on Foundations of Computer Science (Cat. No.91CH3062-7)

    Publication Year: 1991
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    Freely Available from IEEE
  • Fast approximation algorithms for fractional packing and covering problems

    Publication Year: 1991, Page(s):495 - 504
    Cited by:  Papers (26)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (892 KB)

    Fast algorithms that find approximate solutions for a general class of problems, which are called fractional packing and covering problems, are presented. The only previously known algorithms for solving these problems are based on general linear programming techniques. The techniques developed greatly outperform the general methods in many applications, and are extensions of a method previously a... View full abstract»

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  • Discrepancy and ∈-approximations for bounded VC-dimension

    Publication Year: 1991, Page(s):424 - 430
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (524 KB)

    Let (X, R) be a set system on an n-point set X. For a two-coloring on X, its discrepancy is defined as the maximum number by which the occurrences of the two colors differ in any set in R. It is shown that if for any m-point subset Y⊆X the number of distinct subsets induced by R on Y is bounded ... View full abstract»

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  • Simulating BPP using a general weak random source

    Publication Year: 1991, Page(s):79 - 89
    Cited by:  Papers (30)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (932 KB)

    It is shown how to simulate BPP and approximation algorithms in polynomial time using the output from a δ-source. A δ-source is a weak random source that is asked only once for R bits, and must output an R-bit string according to some distribution that places probability no more than 2-δR on any particular string. Also given are two applications: one ... View full abstract»

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  • Dynamic three-dimensional linear programming

    Publication Year: 1991, Page(s):488 - 494
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (592 KB)

    Linear programming optimizations on the intersection of k polyhedra in R3, represented by their outer recursive decompositions, are performed in expected time O(k log k log n+√k log k log3 n). This result is used to derive efficient algorithms for dynamic linear programming problems ill which const... View full abstract»

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  • On selecting a satisfying truth assignment

    Publication Year: 1991, Page(s):163 - 169
    Cited by:  Papers (28)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (524 KB)

    The complexity of certain natural generalizations of satisfiability, in which one of the possibly exponentially many satisfying truth assignments must be selected, is studied. Two natural selection criteria, default preference and minimality (circumscription), are considered. The thrust of the complexity results seems to be that hard problems become harder, while easy problems remain easy. This co... View full abstract»

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  • A quadratic time algorithm for the minmax length triangulation

    Publication Year: 1991, Page(s):414 - 423
    Cited by:  Papers (5)  |  Patents (13)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (920 KB)

    It is shown that a triangulation of a set of n points in the plane that minimizes the maximum edge length can be computed in time O(n2). The algorithm is reasonably easy to implement and is based on the theorem that there is a triangulation with minmax edge length that contains the relative neighborhood graph of the points as a subgraph. With minor modificatio... View full abstract»

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  • Languages that are easier than their proofs

    Publication Year: 1991, Page(s):19 - 28
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (800 KB)

    Languages in NP are presented for which it is harder to prove membership interactively than it is to decide this membership. Similarly, languages where checking is harder than computing membership are presented. Under assumptions about triple-exponential time, incoherent sets in NP are constructed. Without any assumptions, incoherent sets are constructed in DSPACE (n to the log n View full abstract»

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  • Dynamic scheduling on parallel machines

    Publication Year: 1991, Page(s):111 - 120
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (780 KB)

    The problem of online job scheduling on various parallel architectures is studied. An O((log log n)1/2 )-competitive algorithm for online dynamic scheduling on an n ×n mesh is given. It is proved that this algorithm is optimal up to a constant factor. The algorithm is not greedy, and the lower bound proof shows that no greedy-like algorithm can ... View full abstract»

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  • Subquadratic zero-knowledge

    Publication Year: 1991, Page(s):69 - 78
    Cited by:  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (876 KB)

    The communication complexity of zero-knowledge proof systems is improved. Let C be a Boolean circuit of size n. Previous zero-knowledge proof systems for the satisfiability of C require the use of Ω(kn) bit commitments in order to achieve a probability of undetected cheating not greater than 2-k. In the case k=n, the communica... View full abstract»

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  • Polynomial algorithms for LP over a subring of the algebraic integers with applications to LP with circulant matrices

    Publication Year: 1991, Page(s):480 - 487
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (680 KB)

    It is shown that a modified variant of the interior point method can solve linear programs (LPs) whose coefficients are real numbers from a subring of the algebraic integers. By defining the encoding size of such numbers to be the bit size of the integers that represent them in the subring, it is proved that the modified algorithm runs in time polynomial in the encoding size of the input coefficie... View full abstract»

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  • A unified geometric approach to graph separators

    Publication Year: 1991, Page(s):538 - 547
    Cited by:  Papers (47)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (688 KB)

    A class of graphs called k-overlap graphs is proposed. Special cases of k-overlap graphs include planar graphs, k-nearest neighbor graphs, and earlier classes of graphs associated with finite element methods. A separator bound is proved for k-overlap graphs embedded in d dimensions. The result unifies several earlier separator results. All the arguments are base... View full abstract»

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  • Competitive algorithms for layered graph traversal

    Publication Year: 1991, Page(s):288 - 297
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (768 KB)

    A layered graph is a connected, weighted graph whose vertices are partitioned into sets L0={s}, L 1, L2, . . ., and whose edges run between consecutive layers. Its width is max{|Li|}. In the online layered graph traversal problem, a searcher starts at s in a layered graph of unknown width and tries to... View full abstract»

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  • Communication complexity for parallel divide-and-conquer

    Publication Year: 1991, Page(s):151 - 162
    Cited by:  Papers (12)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (888 KB)

    The relationship between parallel computation cost and communication cost for performing divide-and-conquer (D&C) computations on a parallel system of p processors is studied. The parallel computation cost is the maximal number of the D&C nodes that any processor in the parallel system may expand, whereas the communication cost is the total number of cross nodes (nodes generated b... View full abstract»

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  • A general approach to removing degeneracies

    Publication Year: 1991, Page(s):405 - 413
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (732 KB)

    Algorithms modeled as algebraic branching programs, with inputs from an infinite ordered field, are studied. Direct perturbations on the input, so that an algorithm designed under the assumption of nondegeneracy can be applied to all inputs, are described. A deterministic method for algorithms with determinant tests and a randomized one for arbitrary test expressions are defined. They both incur e... View full abstract»

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  • Fully parallelized multi prover protocols for NEXP-time

    Publication Year: 1991, Page(s):13 - 18
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (488 KB)

    A major open problem in the theory of multiprover protocols is to characterize the languages which can be accepted by fully parallelized protocols which achieve an exponentially low probability of cheating in a single round. The problem was motivated by the observation that the probability of cheating the n parallel executions of a multiprover protocol can be exponentially higher than the... View full abstract»

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  • A deterministic parallel algorithm for planar graphs isomorphism

    Publication Year: 1991, Page(s):723 - 732
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (708 KB)

    A deterministic parallel algorithm for determining whether two planar graphs are isomorphic is presented. The algorithm needs O(log n) separators that have to be computed one after the other. The running time is T=O(log3 n) time for finding separators, and the processors count is n1.5 log n/T. It is also ... View full abstract»

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  • On-line scheduling in the presence of overload

    Publication Year: 1991, Page(s):100 - 110
    Cited by:  Papers (45)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (864 KB)

    The preemptive scheduling of sporadic tasks on a uniprocessor is considered. A task may arrive at any time, and is characterized by a value that reflects its importance, an execution time that is the amount of processor time needed to completely execute the task, and a deadline by which the task is to complete execution. The goal is to maximize the sum of the values of the completed tasks. An onli... View full abstract»

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  • The art gallery theorem for polygons with holes

    Publication Year: 1991, Page(s):39 - 48
    Cited by:  Papers (21)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (596 KB)

    Art gallery problems which have been extensively studied over the last decade ask how to station a small (minimum) set of guards in a polygon such that every point of the polygon is watched by at least one guard. The graph-theoretic formulation and solution to the gallery problem for polygons in standard form is given. A complexity analysis is carried out, and open problems are discussed View full abstract»

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  • Walking an unknown street with bounded detour

    Publication Year: 1991, Page(s):304 - 313
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (588 KB)

    A polygon with two distinguished vertices, s and g , is called a street if the two boundary chains from s to g are mutually weakly visible. For a mobile robot with onboard vision, a strategy for finding a short path from s to g in a street not known in advance is described, and it is proved that the length of the path created does not exceed 1+... View full abstract»

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  • Finding k-cuts within twice the optimal

    Publication Year: 1991, Page(s):743 - 751
    Cited by:  Papers (14)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (524 KB)

    Two simple approximation algorithms are presented for the minimum k-cut problem. Each algorithm finds a k-cut having weight within a factor of (2-2/k) of the optimal. One of the algorithms is particularly efficient, requiring a total of only n -1 maximum flow computations for finding a set of near-optimal k-cuts, one for each value of k between... View full abstract»

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  • Quantifying knowledge complexity

    Publication Year: 1991, Page(s):59 - 68
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (824 KB)

    Several alternative ways of defining knowledge complexity are presented, and the relationships between them are explored. The discussion covers inclusion results, separation results, properties of knowledge complexity of languages in the Hint sense, and the knowledge complexity of constant round AM proofs View full abstract»

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  • Shrinkage of de Morgan formulae under restriction

    Publication Year: 1991, Page(s):324 - 333
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (616 KB)

    It is shown that a random restriction leaving only a fraction ∈ of the input variables unassigned reduces the expected de Morgan formula size of the induced function by a factor of O(∈ 1.63). This is an improvement over previous results. The new exponent yields an increased lower bound of approximately n2.63 for the de Morgan formula size of a func... View full abstract»

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  • Adaptive dictionary matching

    Publication Year: 1991, Page(s):760 - 766
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (524 KB)

    Semiadaptive and fully adaptive dictionary matching algorithms are presented. In the fully adaptive algorithm, the dictionary is processed in time O(|D| log |D|). Inserting a new pattern Pk+1 into the dictionary can be done in time O |PK+1| log |D|). A dictionary pattern can be deleted in time O(log |... View full abstract»

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  • Efficient algorithms for dynamic allocation of distributed memory

    Publication Year: 1991, Page(s):470 - 479
    Cited by:  Papers (1)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (784 KB)

    The problem of dynamically allocating and deallocating local memory resources among multiple users in a parallel or distributed system is considered. The goal is to devise an online allocation algorithm that minimizes both the fraction of unused space due to fragmentation of the memory and the slowdown needed by the system to service user requests. The problem is solved in near-optimal fashion by ... View full abstract»

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