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Foundations of Computer Science, 1994 Proceedings., 35th Annual Symposium on

Date 20-22 Nov. 1994

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Displaying Results 1 - 25 of 74
  • Proceedings 35th Annual Symposium on Foundations of Computer Science

    Publication Year: 1994
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    Freely Available from IEEE
  • Set constraints with projections are in NEXPTIME

    Publication Year: 1994 , Page(s): 642 - 653
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (912 KB)  

    Systems of set constraints describe relations between sets of ground terms. They have been successfully used in program analysis and type inference. In this paper we prove that the problem of existence of a solution of a system of set constraints with projections is in NEXPTIME, and thus that it is NEXPTIME-complete. This extends the result of A. Aiken, D. Kozen, and E.L. Wimmers (1993) and R. Gil... View full abstract»

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  • On the combinatorial and algebraic complexity of quantifier elimination

    Publication Year: 1994 , Page(s): 632 - 641
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (712 KB)  

    In this paper we give a new algorithm for performing quantifier elimination from first order formulae over real closed fields. This algorithm improves the complexity of the asymptotically fastest algorithm for this problem, known to this date. A new feature of our algorithm is that the role of the algebraic part (the dependence on the degrees of the input polynomials) and the combinatorial part (t... View full abstract»

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  • A polynomial-time algorithm for deciding equivalence of normed context-free processes

    Publication Year: 1994 , Page(s): 623 - 631
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (652 KB)  

    A polynomial-time procedure is presented for deciding bisimilarity of normed context-free processes. It follows as a corollary that language equivalence of simple context-free grammars is decidable in polynomial time View full abstract»

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  • On the power of quantum computation

    Publication Year: 1994 , Page(s): 116 - 123
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (580 KB)  

    The quantum model of computation is a probabilistic model, similar to the probabilistic Turing Machine, in which the laws of chance are those obeyed by particles on a quantum mechanical scale, rather than the rules familiar to us from the macroscopic world. We present here a problem of distinguishing between two fairly natural classes of function, which can provably be solved exponentially faster ... View full abstract»

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  • Long tours and short superstrings

    Publication Year: 1994 , Page(s): 166 - 177
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (900 KB)  

    This paper considers weight-maximizing variants of the classical symmetric and asymmetric traveling-salesman problems. Like their weight-minimizing counterparts, these variants are MAX SNP-hard. We present the first nontrivial approximation algorithms for these problems. Our algorithm for directed graphs finds a tour whose weight is at least 38/63≈0.603 times the weight of a maximum-weight tour... View full abstract»

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  • Optimizing static calendar queues

    Publication Year: 1994 , Page(s): 732 - 743
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (756 KB)  

    The calendar queue is an important implementation of a priority queue which is particularly useful in discrete event simulators. In this paper we present an analysis of the static calendar queue which maintains N active events. A step of the discrete event simulator removes and processes the event with the smallest associated time and inserts a new event whose associated time is the time of the re... View full abstract»

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  • Nearly tight bounds for wormhole routing

    Publication Year: 1994 , Page(s): 347 - 355
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (676 KB)  

    We present nearly tight bounds for wormhole muting on Butterfly networks which indicate it is fundamentally different from store-and-forward packet routing. For instance, consider the problem of routing N log N (randomly generated) log N length messages from the inputs to the outputs of an N input Butterfly. We show that with high probability that this must take time at least Ω(log... View full abstract»

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  • Fast and feasible periodic sorting networks of constant depth

    Publication Year: 1994 , Page(s): 369 - 380
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (956 KB)  

    A periodic comparator network has depth (or period) k, if for every t>k, the compare-exchange operations performed at step t are executed between exactly the same registers as at step t-k. We introduce a general method that converts an arbitrary comparator network that sorts n items in time T(n) and that has layout area A into a periodic sorting network of depth 5 that sorts Θ(n·T(... View full abstract»

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  • Priority encoding transmission

    Publication Year: 1994 , Page(s): 604 - 612
    Cited by:  Papers (15)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (644 KB)  

    We introduce a novel approach for sending messages over lossy packet-based networks. The new method, called Priority Encoding Transmission, allows a user to specify a different priority on each segment of the message. Based on the priorities, the sender uses the system to encode the segments into packets for transmission. The system ensures recovery of the segments in order of their priority. The ... View full abstract»

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  • A theory of competitive analysis for distributed algorithms

    Publication Year: 1994 , Page(s): 401 - 411
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (904 KB)  

    We introduce a theory of competitive analysis for distributed algorithms. The first steps in this direction were made in the seminal papers of Y. Bartal et al. (1992), and of B. Awerbuch et al. (1992), in the context of data management and job scheduling. In these papers, as well as in other subsequent sequent work, the cost of a distributed algorithm is compared to the cost of an optimal global-c... View full abstract»

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  • Markov chains and polynomial time algorithms

    Publication Year: 1994 , Page(s): 656 - 671
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (1484 KB)  

    This paper outlines the use of rapidly mixing Markov Chains in randomized polynomial time algorithms to solve approximately certain counting problems. They fall into two classes: combinatorial problems like counting the number of perfect matchings in certain graphs and geometric ones like computing the volumes of convex sets View full abstract»

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  • Randomness-efficient oblivious sampling

    Publication Year: 1994 , Page(s): 276 - 287
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (784 KB)  

    We introduce a natural notion of obliviousness of a sampling procedure, and construct a randomness-efficient oblivious sampler. Our sampler uses O(l+log δ-1·log l) coins to output m=poly(ε-1, log δ-1, log l) sample points x1, …, xm, ∈ {0, 1}1 such that Pr[|1/mΣi=1mf(x... View full abstract»

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  • The power of team exploration: two robots can learn unlabeled directed graphs

    Publication Year: 1994 , Page(s): 75 - 85
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (736 KB)  

    We show that two cooperating robots can learn exactly any strongly-connected directed graph with n indistinguishable nodes in expected time polynomial in n. We introduce a new type of homing sequence for two robots which helps the robots recognize certain previously-seen nodes. We then present an algorithm in which the robots learn the graph and the homing sequence simultaneously by wandering acti... View full abstract»

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  • Approximate graph coloring by semidefinite programming

    Publication Year: 1994 , Page(s): 2 - 13
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (948 KB)  

    We consider the problem of coloring k-colorable graphs with the fewest possible colors. We give a randomized polynomial time algorithm which colors a 3-colorable graph on n vertices with min {O(Δ1/3log4/3Δ), O(n1/4 log n)} colors where Δ is the maximum degree of any vertex. Besides giving the best known approximation ratio in terms of n, this mark... View full abstract»

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  • Randomized simplex algorithms on Klee-Minty cubes

    Publication Year: 1994 , Page(s): 502 - 510
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (612 KB)  

    We investigate the behavior of randomized simplex algorithms on special linear programs. For this, we develop combinatorial models for the Klee-Minty cubes (1972) and similar linear programs with exponential decreasing paths. The analysis of two most natural randomized pivot rules on the Klee-Minty cubes leads to (nearly) quadratic lower bounds for the complexity of linear programming with random ... View full abstract»

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  • Measure on small complexity classes, with applications for BPP

    Publication Year: 1994 , Page(s): 807 - 818
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (856 KB)  

    We present a notion of resource-bounded measure for P and other subexponential-time classes. This generalization is based on Lutz's notion of measure, but overcomes the limitations that cause Lutz's definitions to apply only to classes at least as large as E. We present many of the basic properties of this measure, and use it to explore the class of sets that are hard for BPP. Bennett and Gill sho... View full abstract»

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  • Finding the k shortest paths

    Publication Year: 1994 , Page(s): 154 - 165
    Cited by:  Papers (61)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (904 KB)  

    We give algorithms for finding the k shortest paths (not required to be simple) connecting a pair of vertices in a digraph. Our algorithms output an implicit representation of these paths in a digraph with n vertices and m edges, in time O(m+n log n+k). We can also find the k shortest paths from a given source s to each vertex in the graph, in total time O(m+n log n+kn). We describe applications t... View full abstract»

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  • Multi-index hashing for information retrieval

    Publication Year: 1994 , Page(s): 722 - 731
    Cited by:  Papers (7)  |  Patents (21)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (612 KB)  

    We describe a technique for building hash indices for a large dictionary of strings. This technique permits robust retrieval of strings from the dictionary even when the query pattern has a significant number of errors. This technique is closely related to the classical Turan problem for hypergraphs. We propose a general method of multi-index construction by generalizing certain Turan hypergraphs.... View full abstract»

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  • Maximum agreement subtree in a set of evolutionary trees-metrics and efficient algorithms

    Publication Year: 1994 , Page(s): 758 - 769
    Cited by:  Papers (1)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (820 KB)  

    In this paper we prove that the maximum homeomorphic agreement subtree problem is 𝒩𝒫-complete for three trees with unbounded degrees. We then show an approximation algorithm of time O(kn5) for choosing the species that are not in a maximum agreement subtree of a set of k trees. Our approximation is guaranteed to provide a set that is no more than 4 times the optimum solution. ... View full abstract»

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  • More output-sensitive geometric algorithms

    Publication Year: 1994 , Page(s): 695 - 702
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (572 KB)  

    A simple idea for speeding up the computation of extrema of a partially ordered set turns out to have a number of interesting applications in geometric algorithms; the resulting algorithms generally replace an appearance of the input size n in the running time by an output size A⩽n. In particular, the A coordinate-wise minima of a set of n points in Rd can be found by an algorithm n... View full abstract»

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  • Maximum (s,t)-flows in planar networks in O(|V|log|V|) time

    Publication Year: 1994 , Page(s): 178 - 189
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (648 KB)  

    Let G=(V, A) be a directed, planar graph, let s, t ∈ V, s≠t, and let ca>0 be the capacity of an arc a∈A. The problem is to find a maximum flow from s to t in G: subject to these capacities. The fastest algorithm known so far requires 𝒪(|V|·3√|V|·log|V|) time, whereas the algorithm introduced in this paper requires only 𝒪(|V|log|V|... View full abstract»

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  • The complexity of the membership problem for 2-generated commutative semigroups of rational matrices

    Publication Year: 1994 , Page(s): 135 - 142
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (500 KB)  

    We present a deterministic polynomial-time algorithm for the ABC problem, which is the membership problem for 2-generated commutative linear semigroups over an algebraic number field. We also obtain a polynomial time algorithm, for the (easier) membership problem, for 2-generated abelian linear groups. Furthermore, we provide a polynomial-sized encoding for the set of all solutions View full abstract»

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  • Beyond competitive analysis [on-line algorithms]

    Publication Year: 1994 , Page(s): 394 - 400
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (528 KB)  

    The competitive analysis of on-line algorithms has been criticized as being too crude and unrealistic. We propose two refinements of competitive analysis an two directions: The first restricts the power of the adversary by allowing only certain input distributions, while the other allows for comparisons between information regimes for on-line decision-making. We illustrate the first with an applic... View full abstract»

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  • On the computation of Boolean functions by analog circuits of bounded fan-in

    Publication Year: 1994 , Page(s): 553 - 564
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (784 KB)  

    We consider the complexity of computing Boolean functions by analog circuits of bounded fan-in, i.e. by circuits of gates computing real-valued functions, either exactly or as a sign-representation. Sharp upper bounds are obtained for the complexity of the most difficult n-variable function over certain bases (sign-representation by arithmetic circuits and exact computation by piecewise linear cir... View full abstract»

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