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Foundations of Computer Science, 1980., 21st Annual Symposium on

Date 13-15 Oct. 1980

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Displaying Results 1 - 25 of 49
  • [Front cover]

    Publication Year: 1980, Page(s): C1
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    Freely Available from IEEE
  • Table of contents

    Publication Year: 1980, Page(s):iv - vi
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  • Foreword

    Publication Year: 1980, Page(s): iii
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    Freely Available from IEEE
  • On linear characterizations of combinatorial optimization problems

    Publication Year: 1980, Page(s):1 - 9
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1050 KB)

    We show that there can be no computationally tractable description by linear inequalities of the polyhedron associated with any NP-complete combinatorial optimization problem unless NP = co-NP -- a very unlikely event. We also apply the ellipsoid method for linear programming to show that a combinatorial optimization problem is solvable in polynomial time if and only if it admits a small generator... View full abstract»

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  • On a class of totally unimodular matrices

    Publication Year: 1980, Page(s):10 - 16
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (914 KB)

    We examine the class of matrices that satisfy Commoner's sufficient condition for total unimodularity [C], which we call restricted totally unimodular (RTUM). We show that a matrix is RTUM if and only if it can be decomposed in a very simple way into the incidence matrices (or their transposes) of bipartite graphs or directed graphs, and give a linear time algorithm to perform this task. Based on ... View full abstract»

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  • An O(v|v| c |E|) algoithm for finding maximum matching in general graphs

    Publication Year: 1980, Page(s):17 - 27
    Cited by:  Papers (31)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (975 KB)

    In this paper we present an 0(√|V|¿|E|) algorithm for finding a maximum matching in general graphs. This algorithm works in 'phases'. In each phase a maximal set of disjoint minimum length augmenting paths is found, and the existing matching is increased along these paths. Our contribution consists in devising a special way of handling blossoms, which enables an O(|E|) implementation of a... View full abstract»

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  • Some theorems about matrix multiplication

    Publication Year: 1980, Page(s):28 - 35
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (856 KB)

    This paper considers the computation of matrix chain products of the form M1 × M2 ×...× Mn-1. If the matrices are of different dimensions, the order in which the matrices are computed affects the number of operations. An optimum order is an order which minimizes the total number of operations. We present some theorems about an optimum order of computing the matrices. Based on the... View full abstract»

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  • Polynomial-time algorithms for permutation groups

    Publication Year: 1980, Page(s):36 - 41
    Cited by:  Papers (25)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (558 KB)

    A permutation group on n letters may always be represented by a small set of generators, even though its size may be exponential in n. We show that it is practical to use such a representation since many problems such as membership testing, equality testing, and inclusion testing are decidable in polynomial time. In addition, we demonstrate that the normal closure of a subgroup can be computed in ... View full abstract»

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  • Isomorphism of graphs of bounded valence can be tested in polynomial time

    Publication Year: 1980, Page(s):42 - 49
    Cited by:  Papers (9)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (933 KB)

    Suppose we are given a set of generators for a group G of permutations of a colored set A. The color automorphism problem for G involves finding generators for the subgroup of G which stabilizes the color classes. Testing isomorphism of graphs of valence ≤ t is polynomial-time reducible to the color automorphism problem for groups with small simple sections. The algorithm for the latter pr... View full abstract»

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  • A fast algorithm for multiprocessor scheduling

    Publication Year: 1980, Page(s):50 - 53
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (451 KB)

    First Page of the Article
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  • Sparse complete sets for NP: Solution of a conjecture of Berman and Hartmanis

    Publication Year: 1980, Page(s):54 - 60
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (616 KB)

    A set S ⊂ {0,1}* is sparse if there is a polynomial p such that the number of strings in S of size at most n is at most p(n). All known NP-complete sets, such as SAT, are not sparse. The main result of this paper is that if there is a sparse NP-complete set under many-one reductions, then P = NP. We also show that if there is a sparse NP-complete set under Turing reductions, then the polyn... View full abstract»

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  • Efficient algorithms for path system problems and applications to alternating and time-space complexity classes

    Publication Year: 1980, Page(s):62 - 73
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1397 KB)

    Let SPS(f(n)) denote the solvable path system problem for path systems of bandwidth f(n) and SPS (f(n)) the corresponding problem for monotone systems. Let DTISP (poly, f(n)) denote the polynomial time and simultaneous f(n) space class and SC = UkDTISP (poly, logkn). Let ASPACE (f(n)) denote the sets accepted by f(n) space bounded alternating TMs and ASPACE (f(n)) the corresponding one-way TM fami... View full abstract»

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  • Upper and lower bounds for first order expressibility

    Publication Year: 1980, Page(s):74 - 82
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1136 KB)

    We continue the study of first order expressibility as a measure of complexity, introducing the new class Var &Sz[v(n),z(n)] of languages expressible with v(n) variables in sentences of size z(n). We show that when the variables are restricted to boolean values: BVar &Sz[v(n),z(n)] = ASPACE&TIME[v(n),t(n)] That is variables and size correspond precisely to alternating space... View full abstract»

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  • The equivalence problem for deterministic two-way sequential transducers is decidable

    Publication Year: 1980, Page(s):83 - 85
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (303 KB)

    The equivalence problem for deterministic twoway sequential transducers is a long time open problem which is known to be decidable for some restricted cases. Here, the problem is shown to be decidable also for the general case. This even when the devices are allowed to make some finite number of nondeterministic moves. View full abstract»

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  • Succinct representation random strings, and complexity classes

    Publication Year: 1980, Page(s):86 - 95
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    A general paradigm for relating measures of succinctness of representation and complexity theory is presented. The measures are based on the new Private and Blindfold Alternation machines. These measures are used to indicate the inherent information (or "randomness") of a string, but with respect to time and space complexity classes. These measures are then used to show that the existence of strin... View full abstract»

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  • Proofs by induction in equational theories with constructors

    Publication Year: 1980, Page(s):96 - 107
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1285 KB)

    We show how to prove (and disprove) theorems in the initial algebra of an equational variety by a simple extension of the Knuth-Bendix completion algorithm. This allows us to prove by purely equational reasoning theorems whose proof usually requires induction. We show applications of this method to proofs of programs computing over data structures, and to proofs of algebraic summation identities. ... View full abstract»

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  • An improved algorithm for computing with equations

    Publication Year: 1980, Page(s):108 - 117
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1134 KB)

    Implementation of programming language interpreters, proving theorems of the form A=B, and implementation of abstract data types are all problems that can be reduced to the problem of finding a normal form for an expression with respect to a finite set of equation (axiom) schemata The definition of a nonoverlapping s set of axiom schemata is given and the directed congruence closure algorithm is p... View full abstract»

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  • Programs and types

    Publication Year: 1980, Page(s):118 - 128
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1311 KB)

    The first two sections of this paper motivate and outline a constructive theory of (data) types which we developed for formal program verification. The executable component of the theory provides a very high level programming language with a rich type structure. A theory of this generality appears necessary to manage complex programming and formal reasoning about it. The logical component, influen... View full abstract»

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  • Process logic: Expressiveness, decidability, completeness

    Publication Year: 1980, Page(s):129 - 142
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1298 KB)

    We define a process logic PL that subsumes Pratt's process logic, Parikh's SOAPL, Nishimura's process logic, and Pnueli's Temporal Logic in expressiveness. The language of PL is an extension of the language of Propositional Dynamic Logic (PDL). We give a deductive system for PL which includes the Segerberg axioms for PDL and prove that it is complete. We also show that PL is decidable. View full abstract»

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  • A linear history semantics for distributed languages extended abstract

    Publication Year: 1980, Page(s):143 - 151
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    A denotational semantics is given for a distributed language based on communication (CSP). The semantics uses linear sequences of communications to record computations; for any well formed program segment the semantics is a relation between attainable states and the communication sequences needed to attain these states. In binding two or more processes we match and merge the communication sequence... View full abstract»

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  • The complexity of recursion schemes and recursive programming languages

    Publication Year: 1980, Page(s):152 - 160
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1163 KB)

    Deterministic exponential lower time bounds are obtained for analyzing monadic recursion schemes, multi-variable recursion schemes, and recursive programs. The lower bound for multivariable recursion schemes holds for any domain of interpretation with at least two elements. The lower bound for recursive programs holds for any recursive programming language with a nontrivial predicate test (i.e. a ... View full abstract»

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  • On the expressive power of attribute grammars

    Publication Year: 1980, Page(s):161 - 172
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (909 KB)

    We examine the possibility of translating an attribute system into a recursive program scheme taking derivation trees as arguments. This is possible if and only if the attribute system is strongly non-circular. The strong non circularity is decidable in polynomial time. Our recursive program schemes allow us to attack the equivalence problem for attribute systems and solve it in a special case pro... View full abstract»

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  • Loop elimination and loop reduction A model-theoretic analysis of programs

    Publication Year: 1980, Page(s):173 - 184
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    First Page of the Article
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  • Complexity of flow analysis, inductive assertion synthesis and a language due to Dijkstra

    Publication Year: 1980, Page(s):185 - 190
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (642 KB)

    Two different methods of flow analysis are discussed, one a significant generalization of the other. It is shown that the two methods have significantly different intrinsic computational complexities. As an outgrowth of our observations it is shown that a feature of the programming language used by Dijkstra in A Discipline of Programming makes it unsuitable for compile-time type checking, thus sug... View full abstract»

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  • The inherent complexity of dynamic data structures which accommodate range queries

    Publication Year: 1980, Page(s):191 - 199
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1006 KB)

    A formal framework is presented in which to explore the complexity issues of data structures which accommodate various types of range queries. Within this framework, a systematic and reasonably tractable method for assessing inherent complexity is developed. Included among the interesting results are the following: the fact that non-linear lower bounds are readily accessible, and the existence of ... View full abstract»

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