Showing papers in "Theoretical Computer Science in 1988"

TL;DR: This contribution was made possible only by the miraculous fact that the first members of the Editorial Board were sharing the same conviction about the necessity of Theoretical Computer Science.

TL;DR: A polynomial algorithm for determining if two structures are stuttering equivalent is given and the relevance of the results for temporal logic model checking and synthesis procedures is discussed.

TL;DR: The purpose of this paper is to report the development of the first real-time models of CSP to be compatible with the properties and proof systems of the abovementioned untimed models.

TL;DR: This work investigates the problem of representing acyclic digraphs in the plane in such a way that all edges flow in the same direction, e.g., from the left to the right or from the bottom to the top.

TL;DR: It is found that the equational theory of sets, pomsets under concatenation, parallel composition and union is finitely axiomatizable, whereas the theory of languages under the analogous operations is not.

TL;DR: It is shown that there exist exponentially many square-free and cube-free strings of each length over these alphabets and arguments for the nonexistence of various RT(n)th power-free homomorphisms are provided.

TL;DR: Although traditionally most of the development in the theory of traces follows the string-language-theoretic line, it is demonstrated to the reader that the graph- theoretic point of view may be more appropriate.

TL;DR: The Min Cut Linear Arrangement Problem is NP-complete for trees with polynomial size edge weights and this is used to show the NP-completeness of Search Number, Vertex Separation, Progressive Black/White Pebble Demand, and Topological Bandwidth for planar graphs with maximum vertex degree 3.

TL;DR: More standard proof systems and semantics are provided and part of Girard's results are extended by investigating the consequence relations associated with Linear Logic and by proving corresponding Strong completeness theorems.

TL;DR: A logical system and a family of models are proposed, a completeness result is proved and a decision procedure described, and one interpretation of belief which obeys a very strong persistence axiom is put forward and used in the analysis of the “wise men” puzzle.

TL;DR: Abstract Linear Logic provides a refinement of functional programming and suggests a new implementation technique, with the following features: a synthesis of strict and lazy evaluation, a clean semantics of side effects, and no garbage collector.

TL;DR: A calculus of concurrent processes is proposed that embodies the ability to regard a finite computation as a single event, in dealing with the semantics of concurrency, and shows that this abstraction mechanism, together with the idea of compound actions, allows us to deal with a variety of synchronization and communication disciplines.

TL;DR: An improvement on the algorithm for finding the transitive closure of an acyclic digraph G with worst case runtime O(n·ered) and space O( n·k, where k is the width of a chain decomposition.

TL;DR: Techniques for studying complexity classes that are not covered by known recursive enumerations of machines are developed by using them to examine the probabilistic class BPP and it is shown that there is a relativized world where BPPA has no complete languages.

TL;DR: Results of Haken are extended to give an exponential lower bound on the size of resolution proofs for propositional formulas encoding a generalized pigeonhole principle, showing that resolution proof systems do not p-simulate constant-formula-depth Frege proof systems.

TL;DR: A syntax-directed generalization of Owicki–Gries's Hoare logic for a parallel while language is presented, based on Hoare asserted programs of the form {Γ, A } p { B, Δ} where Γ, Δ are sets of first-order formulas.

TL;DR: A procedure is shown, building the principal type scheme of a term through the construction of the most general unifier for intersection type schemes.

TL;DR: A general method for parallelisation for the same class of problems on more powerful parallel computers is presented and it is shown that the dynamic programming problems considered can be computed in log2n time using n6/log(n) processors on a parallel random access machine without write conflicts.

TL;DR: An E-unification algorithm based on flattening and SLD-resolution is developed and proved sound and complete by establishing a correspondence between narrowing sequences and resolution sequences.

TL;DR: It is shown that if the problem of finding a minimum dominating set in a tournament can be solved in n O(log n ) time, then for every constant C, there is also a polynomial-time algorithm for the satisfiability problem of boolean formulas in conjunctive normal form with m clauses and C log 2 m variables.

TL;DR: An effective criterion for determining whether a given language has dot-depth 2 is conjecture and the condition is shown to be necessary in general, and sufficient for languages over a two-letter alphabet.

TL;DR: Several facts about multihead pushdown automata are obtained, indicating that the study of alternating multihead finite automata may lead to useful results about nonalternating automata.

TL;DR: Clause implication is shown to be undecidable using the undecidability of finitely generated stable transitive relations on free terms to reduce the search space in Automated Deduction Systems.

TL;DR: The results presented in this paper concern the axiomatizability problem of first-order temporal logic with linear and discrete time and show that the logic is incomplete, i.e., it cannot be provided with a finitistic and complete proof system.

TL;DR: The uniform tag sequences of Cobham are generalized to the case where the homomorphism ϕ is not necessarily uniform, but rather satisfies the analogue of an algebraic equation.

TL;DR: The relationships among these problems as well as prove some positive results concerning CA's are investigated, and it is shown that the languageL={0n1m|m,n>0, mdividesn}is a real-time CA language, disproving a conjecture of Bucher and Culik.

TL;DR: In this article, the authors present an algorithm for constraining dans l'ordre la liste des mots de Lyndon de longueur donnee, a mot primitif, which is the mot that is le plus petit mot in sa classe de conjugaison.

TL;DR: The NP-completeness of the ∃∀∀-class is used to prove that for certain formulas there exist no equivalent quantifier-free formulas of polynomial length.

TL;DR: An axiomatic theory of sets and rules is formulated, which permits the use of sets as data structures and allows rules to operate on rules, numbers, or sets, and which combines the λ-calculus with traditional set theories.