Proceedings of IEEE 36th Annual Foundations of Computer Science

23-25 Oct. 1995

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Displaying Results 1 - 25 of 74
  • Lower bounds for monotone span programs

    Publication Year: 1995, Page(s):674 - 681
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (796 KB)

    Span programs provide a linear algebraic model of computation. Lower Bounds for span programs imply lower bounds for formula size, symmetric branching programs and for contact schemes. Monotone span programs correspond also to linear secret-sharing schemes. We present a technique for proving lower bounds for monotone span programs, and prove a lower bound of Ω(m/sup 2.5/) for the 6-clique ... View full abstract»

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  • Author index

    Publication Year: 1995
    Request permission for commercial reuse | PDF file iconPDF (103 KB)
    Freely Available from IEEE
  • The resolution of a Hartmanis conjecture

    Publication Year: 1995, Page(s):362 - 371
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (776 KB)

    Building on the recent breakthrough by M. Ogihara (1995), we resolve a conjecture made by J. Hartmanis (1978) regarding the (non) existence of sparse sets complete for P under logspace many-one reductions. We show that if there exists a sparse hard set for P under logspace many-one reductions, then P=LOGSPACE. We further prove that if P has a sparse hard set under many-one reductions computable in... View full abstract»

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  • Sparse P-hard sets yield space-efficient algorithms

    Publication Year: 1995, Page(s):354 - 361
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (500 KB)

    J. Hartmanis (1978) conjectured that there exist no sparse complete sets for P under logspace many-one reductions. In this paper, in support of the conjecture, it is shown that if P has sparse hard sets under logspace many-one reductions, then P⊆DSPACE[log2n]. The result follows from a more general statement: if P has 2polylog sparse hard sets under poly-logarithmic spac... View full abstract»

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  • Amortization, lazy evaluation, and persistence: lists with catenation via lazy linking

    Publication Year: 1995, Page(s):646 - 654
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (680 KB)

    Amortization has been underutilized in the design of persistent data structures, largely because traditional accounting schemes break down in a persistent setting. Such schemes depend on saving “credits” for future use, but a persistent data structure may have multiple “futures”, each competing for the same credits. We describe how lazy evaluation can often remedy this prob... View full abstract»

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  • RSPACE(S)⊆DSPACE(S3/2)

    Publication Year: 1995, Page(s):344 - 353
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (848 KB)

    We prove that any language that can be recognized by a randomized algorithm (with possibly two-sided error) that runs in space S and expected time 20(s) can be recognized by a deterministic algorithm running in space S3/2. This improves over the best previously known result that such algorithms have deterministic space S 2 simulations which, for one-sided error alg... View full abstract»

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  • A unified analysis of paging and caching

    Publication Year: 1995, Page(s):194 - 203
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (868 KB)

    Paging (caching) is the problem of managing a two-level memory hierarchy in order to minimise the time required to process a sequence of memory accesses. In order to measure this quantity, we define the system parameter miss penalty to represent the extra time required to access slow memory. In the context of paging, miss penalty is large, so most previous studies of on-line paging have implicitly... View full abstract»

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  • Contention resolution with bounded delay

    Publication Year: 1995, Page(s):104 - 113
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1020 KB)

    When distributed processes contend for a shared resource, we need a good distributed contention resolution protocol, e.g., for multiple-access channels (ALOHA, Ethernet), PRAM emulation, and optical routing. Under a stochastic model of request generation from n synchronous processes, Raghavan & Upfal (1995) have shown a protocol which is stable for a positive request rate; their main result is... View full abstract»

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  • Reconstructing strings from substrings in rounds

    Publication Year: 1995, Page(s):613 - 620
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (720 KB)

    We establish a variety of combinatorial bounds on the tradeoffs inherent in reconstructing strings using few rounds of a given number of substring queries per round. These results lead us to propose a new approach to sequencing by hybridization (SBH), which uses interaction to dramatically reduce the number of oligonucleotides used for de novo sequencing of large DNA fragments, while preserving th... View full abstract»

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  • Efficient access to optical bandwidth wavelength routing on directed fiber trees, rings, and trees of rings

    Publication Year: 1995, Page(s):548 - 557
    Cited by:  Papers (25)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (800 KB)

    We address efficient access to bandwidth in WDM (wavelength division multiplexing) optical networks. We consider tree topologies, ring topologies, as well as trees of rings. These are topologies of concrete practical relevance for which undirected underlying graph models have been studied before by P. Raghavan and E. Upfal (1993). As opposed to previous studies (A. Aggarwal et al., 1993; R. Pankaj... View full abstract»

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  • Markov chain algorithms for planar lattice structures

    Publication Year: 1995, Page(s):150 - 159
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1016 KB)

    Consider the following Markov chain, whose states are all domino tilings of a 2n×2n chessboard: starting from some arbitrary tiling, pick a 2×2 window uniformly at random. If the four squares appearing in this window are covered by two parallel dominoes, rotate the dominoes in place. Repeat many times. This process is used in practice to generate a random tiling and is a key tool in th... View full abstract»

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  • An approximation scheme for planar graph TSP

    Publication Year: 1995, Page(s):640 - 645
    Cited by:  Papers (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (504 KB)

    We consider the special case of the traveling salesman problem (TSP) in which the distance metric is the shortest-path metric of a planar unweighted graph. We present a polynomial-time approximation scheme (PTAS) for this problem View full abstract»

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  • Efficient algorithms for learning to play repeated games against computationally bounded adversaries

    Publication Year: 1995, Page(s):332 - 341
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1100 KB)

    We examine the problem of learning to play various games optimally against resource-bounded adversaries, with an explicit emphasis on the computational efficiency of the learning algorithm. We are especially interested in providing efficient algorithms for games other than penny-matching (in which payoff is received for matching the adversary's action in the current round), and for adversaries oth... View full abstract»

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  • Splitters and near-optimal derandomization

    Publication Year: 1995, Page(s):182 - 191
    Cited by:  Papers (40)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (980 KB)

    We present a fairly general method for finding deterministic constructions obeying what we call k-restrictions; this yields structures of size not much larger than the probabilistic bound. The structures constructed by our method include (n,k)-universal sets (a collection of binary vectors of length n such that for any subset of size k of the indices, all 2k configurations appear) and f... View full abstract»

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  • A representation of cuts within 6/5 times the edge connectivity with applications

    Publication Year: 1995, Page(s):92 - 102
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1192 KB)

    Let G be an undirected c-edge connected graph. In this paper we give an O(n2)-sized planar geometric representation for all edge cuts with capacity less than 6/5c. The representation can be very efficiently built, by using a single run of the Karger-Stein algorithm for finding near-mincuts. We demonstrate that the representation provides an efficient query structure for near-mincuts, as... View full abstract»

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  • Optimal on-line search and sublinear time update in string matching

    Publication Year: 1995, Page(s):604 - 612
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (760 KB)

    We study in a dynamic setting the problem of online searching for the occurrences of an arbitrary pattern string P[1,p] in an indexed text string T[1,n]. That is, we assume that the text T may be updated by inserting or deleting an arbitrary string Y[1,y]. Our main contribution is presenting the first dynamic algorithm that achieves optimal time, i.e. Θ(p+occ), to find the occ occurrences of... View full abstract»

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  • Hard-core distributions for somewhat hard problems

    Publication Year: 1995, Page(s):538 - 545
    Cited by:  Papers (46)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (632 KB)

    Consider a decision problem that cannot be 1-δ approximated by circuits of a given size in the sense that any such circuit fails to give the correct answer on at least a δ fraction of instances. We show that for any such problem there is a specific “hard core” set of inputs which is at least a δ fraction of all inputs and on which no circuit of a slightly smaller size... View full abstract»

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  • Divide-and-conquer approximation algorithms via spreading metrics

    Publication Year: 1995, Page(s):62 - 71
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (792 KB)

    We present a novel divide-and-conquer paradigm for approximating NP-hard graph optimization problems. The paradigm models graph optimization problems that satisfy two properties: First, a divide-and-conquer approach is applicable. Second, a fractional spreading metric is computable in polynomial time. The spreading metric assigns fractional lengths to either edges or vertices of the input graph, s... View full abstract»

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  • An optimal algorithm for Monte Carlo estimation

    Publication Year: 1995, Page(s):142 - 149
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (592 KB)

    A typical approach to estimate an unknown quantity μ is to design an experiment that produces a random variable Z distributed in [O,1] with E[Z]=μ, run this experiment independently a number of times and use the average of the outcomes as the estimate. In this paper, we consider the case when no a priori information about Z is known except that is distributed in [0,1]. We describe an approxi... View full abstract»

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  • Faster algorithms for the construction of parameterized suffix trees

    Publication Year: 1995, Page(s):631 - 638
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (444 KB)

    Parameterized strings were introduced by Baker to solve the problem of identifying blocks of code that get duplicated in a large software system. Parameter symbols capture the notion of code identity while permitting renaming of variables. The code duplication problem was solved by first constructing a generalized suffix tree for the corresponding parameterized strings. The fastest known generaliz... View full abstract»

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  • Gambling in a rigged casino: The adversarial multi-armed bandit problem

    Publication Year: 1995, Page(s):322 - 331
    Cited by:  Papers (84)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (836 KB)

    In the multi-armed bandit problem, a gambler must decide which arm of K non-identical slot machines to play in a sequence of trials so as to maximize his reward. This classical problem has received much attention because of the simple model it provides of the trade-off between exploration (trying out each arm to find the best one) and exploitation (playing the arm believed to give the best payoff)... View full abstract»

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  • Load balancing in the Lp norm

    Publication Year: 1995, Page(s):383 - 391
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (608 KB)

    In the load balancing problem, there is a set of servers, and jobs arrive sequentially. Each job can be run on some subset of the servers, and must be assigned to one of them in an online fashion. Traditionally, the assignment of jobs to servers is measured by the L∞ norm; in other words, an assignment of jobs to servers is quantified by the maximum load assigned to any server. In... View full abstract»

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  • Speed is as powerful as clairvoyance [scheduling problems]

    Publication Year: 1995, Page(s):214 - 221
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (668 KB)

    We consider several well known nonclairvoyant scheduling problems, including the problem of minimizing the average response time, and best-effort firm real-time scheduling. It is known that there are no deterministic online algorithms for these problems with bounded (or even polylogarithmic in the number of jobs) competitive ratios. We show that moderately increasing the speed of the processor use... View full abstract»

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  • Fault diagnosis in a flash

    Publication Year: 1995, Page(s):571 - 580
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (888 KB)

    Consider a set of n processors that can communicate with each other. Assume that each processor can be either “good” or “faulty”. Also assume that the processors can test each other. We consider how to use parallel testing rounds to identify the faulty processors, given an upper bound t on their number. We prove that 4 rounds are necessary and sufficient when 2√(2n)&l... View full abstract»

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  • Synthesizers and their application to the parallel construction of pseudo-random functions

    Publication Year: 1995, Page(s):170 - 181
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1060 KB)

    We present a new cryptographic primitive called pseudo-random synthesizer and show how to use it in order to get a parallel construction of a pseudo-random function. We show an NC1 implementation of pseudo-random synthesizers based on the RSA or the Diffie-Hellman assumptions. This yields the first parallel (NC2 ) pseudo-random function and the only alternative to the origina... View full abstract»

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