Showing papers in "Journal of Computer and System Sciences in 1980"

TL;DR: An algorithm is described for computing the edit distance between two strings of length n and m, n ⪖ m, which requires O(n · max(1, mlog n) steps whenever the costs of edit operations are integral multiples of a single positive real number and the alphabet for the strings is finite.

TL;DR: The main result is a polynomial-time algorithm for the special case of patterns containing only one variable symbol (possibly occurring several times in the pattern).

TL;DR: It is shown that if Π is nontrivial and hereditary on induced subgraphs, then the node-deletion problem forΠ is NP-complete for both undirected and directed graphs.

TL;DR: The main result is the completeness of a simple programming language which can be thought of as consisting of the relational algebra augmented with the power of iteration.

TL;DR: In this paper, the size of an accepting computation tree of an alternating Turing machine (ATM) is introduced as a complexity measure, and a number of applications of tree-size to the study of more traditional complexity classes are presented.

TL;DR: A classification of convex NP -optimization problems is introduced and is applied to study the combinatorial structure of several optimization problems associated to well-known NP -complete sets and it is shown that structurally isomorphic problems have similar approximability properties.

TL;DR: NP-completeness results dealing with sets of strings over both finite and infinite alphabets are presented and a linear time algorithm is given for the restricted version of the superstring problem.

TL;DR: This work analyzes the computational complexity of determining whether F is satisfiable when F is a formula of the classical predicate calculus obeying certain syntactic restrictions and obtains lower and upper nondeterministic time bounds of the form cn/log n.

TL;DR: In this article, the problem of identifying an unknown value x ϵ {1, 2,…, n } using only comparisons of x to constants when as many as E of the comparisons may receive erroneous answers was considered.

TL;DR: An algorithm for "before-after" reasoning about action that decides satisfiability and validity of formulas of propositional dynamic logic, a recently developed logic of change of state that subsumes the zero-order component of most other action-oriented logics.

TL;DR: A relationship between parallel rewriting systems and two-way machines is investigated, finding restrictions on the “copying power” of these devices endow them with rich structuring and give insight into the issues of determinism, parallelism, and copying.

TL;DR: It is shown that context-free sets of finite and infinite words give a natural way of associating to a language a set of infinite words, and it then becomes possible to begin a study of families of sets of infinite Words rather similar to the classical studies of family of languages.

TL;DR: It is shown that for every n , there is a language which is accepted by an n -state nondeterministic one-way finite automaton, yet which is not accepted by any sweeping automaton with fewer than 2 n states.

TL;DR: The problem of finding a homeomorphic image of a "pattern" graph H in a larger input graph G is studied in this article, where the main result is a linear time algorithm to determine if there exists a simple cycle containing three given nodes in G (here H is a triangle).

TL;DR: It is demonstrated that the upper bound can be reduced to O(N 1 3 log N) if arrangements other than fixed partial orders are used.

TL;DR: Time-space tradeoffs for register allocation strategies of any set of expressions which compute given functions have been investigated in this article, where the tradeoff for pebbling superconcentrators and grates has been investigated.

TL;DR: It is shown that in the R-trivial case the required congruence also takes into account the order in which these subwords first appear, from left to right.

TL;DR: An O(EV log2 V) algorithm for finding the maximal flow in networks is described, which is asymptotically better than the other known algorithms if E = O(V2−ϵ) for some ϵ > 0.1.

TL;DR: This paper uses the techniques of recursive function theory, including recursion theorems and priority arguments to prove the independence of certain control structures in abstract programming systems.

TL;DR: An efficient algorithm for solving the graph-realization problem by means of PQ -graphs is presented and it is shown that the value of α(ν, k ) is not more than 3 for all practical values of ν and k, so the problem can be solved in a running time almost proportional to ν, the number of nonzero elements of N.

TL;DR: It is shown that conditions that have appeared in the literature with the purpose of defining a “good” decomposition of a relation scheme are equivalent in the case that all constraints in the database are functional dependencies.

TL;DR: Because the lockout problem is equivalent to the problem of determining whether a player has a winning strategy in a certain kind of game, it can be shown that solving the lockout Problem requires exponential time.

TL;DR: It is shown that for every language L (with the exception of some trivial cases), there is a word w such that, for any pair (g, h), g and h are equivalent on L if and only if g(w) = h(w).

TL;DR: The reachability problem for such Vector Addition Systems is shown to be decidable and an algorithm is designed to decide whether these conditions are satisfied.

TL;DR: A necessary and sufficient condition for a constraint to be a consequence of other constraints of the same family is proved, using the duality between crosses and decompositions.

TL;DR: It is shown that for multihead and multitape Post machines linear time is no more powerful than real time, and two Post tapes or, alternatively, three heads on one Post tape are as powerful as any finite number of heads or tapes.

TL;DR: The quotient construction allows a reconciliation of the equational and synthetic approaches to abstract data types as well as some constructions relating to ordered and complete algebras.

TL;DR: The class of all nondeterministic programming languages with a fixed syntax is shown to be a variety of algebras, and all classes of deterministic Programming languages that allow branching are shows to be nonvarietal.

TL;DR: The main results of this paper concern reducibility, closure properties, generators and hierarchies of language families, as well as the characterization of grammar forms generating (under strict interpretation) the families of regular and linear languages.

TL;DR: The algorithm for determining whether a cubic graph can be imbedded in the torus produced an imbedding in the affirmative and has running time bounded by a polynomial in the number of vertices of the graph.