Showing papers in "Journal of Computer and System Sciences in 1978"

TL;DR: This work presents a formal type discipline for polymorphic procedures in the context of a simple programming language, and a compile time type-checking algorithm w which enforces the discipline.

TL;DR: A number of two-person games, based on simple combinatorial ideas, for which the problem of deciding whether the first player can win is complete in polynomial space provides strong evidence, although not absolute proof, that efficient general algorithms for deciding the winner of these games do not exist.

TL;DR: The decision problem for the theory of integers under addition, or “Presburger Arithmetic,” is proved to be elementary recursive in the sense of Kalmar and it is proved that a quantifier elimination decision procedure for this theory determines the truth of any sentence of length n within deterministic time.

TL;DR: An algorithm is presented that finds K, the set of all keys for agiven set A of attribute names and a given set D [0] of functional dependencies, in time polynomial in A, D, and |K|.

TL;DR: The hierarchy is infinite for any alphabet with two or more letters; over an alphabet of one letter the hierarchy is finite; in fact, B(2) = B(1).

TL;DR: In mathematical semantics, in the sense of Scott, the question arises of what domains of interpretation should be chosen as mentioned in this paper, and it has been felt by the author, and others, that lattices are the wrong choice and instead one should use complete partial orders (cpo's), which do not necessarily have the embarrassing top element.

TL;DR: In this article, the two digraphs, while different, usually represent the same phenomenon, say, the same computational process, and the unfolding (i.e., the trees) are surrogates for the phenomena.

TL;DR: It is shown that for the two-variable quadratics of the form αx2 + βy − γ = 0; α, β, γ ϵ ω, the problem is NP-complete, which implies NP-completeness of certain questions about the solutions.

TL;DR: Another O(n) algorithm simpler than that presented by Spira and Pan for the insertion of a vertex is presented and labels the vertices of the graph in such a way that any vertex may be deleted from the graph and the minimal spanning tree can be updated in constant time.

TL;DR: The result presented here is the first lower bound of better than n log n given for an NP-complete problem for a model that is actually used in practice and derived by combining results on linear search tree complexity with results from threshold logic.

TL;DR: In the main theorem, an algorithm is presented for deciding whether two given homomorphisms are equivalent on a given context-free language and whether the translations defined by two deterministic gsm mappings agree on agiven context- free language.

TL;DR: It is proved that double hashing is asymptotically equivalent to uniform probing for load factors α not exceeding a certain constant α 0 = 0.31….

TL;DR: Algebraic characterizations are obtained for each of the classes of ω-DCFL's, showing certain decision problems, generally undecidable, to be decidable within some of these classes.

TL;DR: The theory of finite automata and regular expressions over a finite alphabet Σ is generalized to infinite tapes X = X 1 … X k, where X i, are themselves tapes of length ω n, and the equivalence of deterministic and nondeterministic automata is proved.

TL;DR: A step-by-step expository analysis of the behavior of information retrieval algorithms under random deletions, as well as random insertions is given, and it is shown how the difficulties arise and can be surmounted.

TL;DR: The problem of firing squad synchronization problem for the class of all polyautomata networks N satisfying the following conditions has a solution: N is connected, the connections of N are bilateral (that is, each connection carries information in both directions).

TL;DR: Switching networks of the type used in telephone exchanges are studied, with emphasis on a particular class of networks possessing great structural symmetry, and it is shown that there are non-blocking networks with roughly 90N log 3 N contacts.

TL;DR: The interest in rooted trees stems from the fact that these two digraphs “unfold” into the SAME infinite tree.

TL;DR: It is shown that for every infinite, coinfinite recursive set A there exists a set B which can be accepted in real time and log space such that B splits A.

TL;DR: There are nondeterministic context-free languages that cannot be expressed as a Boolean formula over deterministic Context-Free languages that do not yield closure under complementation.

TL;DR: Asynchronous cell spaces are capable of simulating the behavior of (non-)deterministic synchronous spaces in the sense that the same sequence of infinite configurations is produced.

TL;DR: A small modification of this algorithm yields a real-time Turing machine algorithm which finds all initial palindromes in the input string.

TL;DR: This paper indicates in this Note how one may construct a computation and construction universal, concurrent, asynchronous, cellular automaton where no overlapping can possibly occur.

TL;DR: This paper defines security policies and protection mechanisms precisely and bridges the gap between them with the concept of soundness: whether a protection mechanism enforces a policy.

TL;DR: Pumping lemmas are stated and proved for the classes of regular and context-free sets of terms and applied to solve decision problems concerning these classes of sets.

TL;DR: Some new results about automorphism groups of strongly connected automata are obtained by making use of a new type of representation of stronglyconnected automata introduced.

TL;DR: The principal technical results show that there exist polynomials f, g, and h with h = fg, such that h requires substantially fewer arithmetic operations than either f or g.

TL;DR: If a language is accepted by a deterministic (nondeterministic) one-way stack automaton then it is the image under a nonerasing homomorphism of a language accepted by the deterministic Turing machine that operates within space log n.

TL;DR: A novel formulation of tessellation structures is introduced which emphasizes the connection between these structures and concepts of functional analysis and a behavioral analysis technique is developed which implies the earlier results on pattern reproduction.