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Showing papers in "Journal of Computer and System Sciences in 1982"


Journal ArticleDOI
TL;DR: In this paper, it was shown that testing isomorphism of graphs of bounded valance is polynomial-time reducible to the color automorphism problem for groups with composition factors of bounded order.

644 citations


Journal ArticleDOI
Ashok K. Chandra1, David Harel1
TL;DR: In this article, a fixpoint query hierarchy is proposed to classify queries on relational data bases according to their structure and their computational complexity using the operations of composition and fixpoints, and a Σ-π hierarchy of height ω2 is defined, and its properties investigated.

559 citations


Journal ArticleDOI
TL;DR: It is shown that the natural classification of events depending on these quantifiers will not yield on infinite hierarchy, and that the latter two hierarchies have appealing characterizations in symbolic logic.

339 citations


Journal ArticleDOI
TL;DR: If there is a sparse NP-complete set under polynomial-time many-one reductions, then P = NP, and it is shown that if there is one, then the polynometric-time hierarchy collapses to Δ2P.

295 citations


Journal ArticleDOI
TL;DR: This work shows how to prove (and disprove) theorems in the initial algebra of an equational variety by a simple extension of the Knuth-Bendix completion algorithm, and applications to proofs of programs computing over data structures, and to algebraic summation identities.

284 citations


Journal ArticleDOI
TL;DR: The average height of a binary tree with n internal nodes is shown to be asymptotic to 2√ πn .

277 citations


Journal ArticleDOI
TL;DR: Algorithms are presented that run in time which depends nontrivially on the rank k of the element to be selected and which is sublinear with respect to set cardinality, and all bounds are shown to be optimal to within a constant multiplicative factor.

265 citations


Journal ArticleDOI
TL;DR: An "alternating pebbling game" is introduced to prove lower bounds on the number of variables and size needed to express properties without successor.

257 citations


Journal ArticleDOI
TL;DR: There exists an algorithm for deciding whether or not an arbitrary finite automaton with a distance function is limited in distance, and it is shown that this paper shows that this algorithm is available.

152 citations


Journal ArticleDOI
TL;DR: A deductive system for PL which includes the Segerberg axioms for PDL and it is proved that it is complete and that PL is decidable.

147 citations


Journal ArticleDOI
TL;DR: A complete axiomatization for deterministic propositionalynamic logic is given, based on the Segerberg axoms for propositional dynamic logic.

Journal ArticleDOI
TL;DR: This work introduces the idea of employing randomization in the mutual exclusion protocol and achieve a mutual exclusion, and with probability 1 lockout-free and bounded-waiting, solution using just a 4 · log2 N-valued shared variable.

Journal ArticleDOI
TL;DR: An attribute grammar is simple multi-visit if each attribute of a nonterminal has a fixed visit- number associated with it such that, during attribute evaluation, the attributes of a node which have visit-number j are computed at the jth visit to the node.

Journal ArticleDOI
Michael Rodeh1
TL;DR: This work considers the problem of computing the median of a bag of 2n numbers by using communicating processes, each having some of the numbers in its local memory, and gives an algorithm that is optimal up to a constant.

Journal ArticleDOI
TL;DR: Three theorems are proven which reconsider the completeness of Hoare's logic for the partial correctness of while-programs equipped with a first-order assertion language.

Journal ArticleDOI
Ker-I Ko1
TL;DR: The result that NP real numbers cannot be polynomial time many-one complete in NP (unless P = NP) shows a basic difference between the maximum value problem and many natural NP combinatorial problems.

Journal ArticleDOI
TL;DR: A technique is developed for determining space complexity in on-line computation and it is shown that each of the following functions requires linear space.

Journal ArticleDOI
Nicholas Pippenger1
TL;DR: It is shown that every n-superconcentrator of depth 2 has size μ(n log n); and that there exist n- superconcentrators on which the pebble game can be played in space S and time O(( n log n)2S), for a wide range of values of S.

Journal ArticleDOI
TL;DR: A new computation system formulation is introduced and general notions of homomorphisms and isomorphisms between computation systems are developed that show that vector replacement systems can be simulated by vector addition systems, and that generalized Petri nets can be emulated by Petrinets.

Journal ArticleDOI
TL;DR: A single construction yields Mahaney's result for sparse ⩽TP-complete sets for NP and also the corresponding result for co-sparse⩽ TP-complete set for NP, which strengthen the earlier work of Karp, Lipton, and Sipser.

Journal ArticleDOI
TL;DR: This work proves the existence of free continuous algebras by actually giving a concrete description of them in terms of trees, for any type of algebra and any choice of the “specified” joins.

Journal ArticleDOI
TL;DR: An O( n 2 · k ) algorithm for constructing the centralizer of a permutation group of degree n presented by a generating set of k permutations is given, and results about the group-theoretic structure of thecentralizer are recovered.

Journal ArticleDOI
TL;DR: It is shown that the equivalence problem for LL-regular grammars is decidable by reducing it to the equivalences problem for real-time strict deterministic Grammars.

Journal ArticleDOI
TL;DR: These results are relevant to the extended definable languages, to the syntax-directed translation of context-free languages, and to the tree transducer hierarchy.

Journal ArticleDOI
TL;DR: This paper studies a class of resource tradeoffs that arise in such problems as parallel sorting algorithms, linear recursion schemata, VLSI layouts, and searching algorithms, and shows that the approach can also lead to lower bounds.

Journal ArticleDOI
TL;DR: The principal regulated rational cone of one-counter “languages” is considered and generalizing Wechler's pushdown automata and pushdown transition matrices yields a characterization of the A -semi-algebraic power series in terms of acceptance by pushdown automation.

Journal ArticleDOI
TL;DR: The method of composing processes generalizes the operations on derivation trees of context-free grammars and Church-Rosser properties of processes are stated.

Journal ArticleDOI
TL;DR: An infinite hierarchy of real-time deterministic context free languages is introduced and it is shown that equivalence of two deterministic languages, one of which is real- time of finite rank in the hierarchy, is also decidable.

Journal ArticleDOI
TL;DR: The existence of a System function is shown: a kind of Combinatorial System defined by Cleave such that arbitrary distinct recursively enumerable one-one degrees can be represented by distinct decision problems for this System function.

Journal ArticleDOI
TL;DR: It is shown that eight multiplications are necessary and sufficient to calculate the four-dimensional quaternion product over Z 2 and the lower bound constructed also represents an upper bound and, hence, the rank.