Showing papers in "Journal of Computer and System Sciences in 1981"

TL;DR: Several new classes of hash functions with certain desirable properties are exhibited, and two novel applications for hashing which make use of these functions are introduced, including a provably secure authentication technique for sending messages over insecure lines and the application of testing sets for equality.

TL;DR: Two complementary but equivalent semantic interpretations of a high level probabilistic programming language are given and how the ordered domains of Scott and others are embedded naturally into these spaces.

TL;DR: A fully dynamic maintenance algorithm for convex hulls that can process insertions and deletions of single points in only O(log* n) steps per transaction, where n is the number of points currently in the set.

TL;DR: A direct way to construct a family of l inear concentrators using Pinsker’s linear concentrators and disproved a conjecture that superconcentrators require more than a linear number of edges.

TL;DR: It is argued that uniform circuit complexity introduced by Borodin is a reasonable model of parallel complexity and that context-free language recognition is in NC, the class of polynomial size andPolynomial-in-log depth circuits.

TL;DR: A new complexity measure is introduced, QN[f(n), which measures the size of sentences from predicate calculus needed to express a given property, and Fraisse-Ehrenfeucht games are used to prove sharp lower bounds in the measure.

TL;DR: A complete description of the Knuth-Bendix completion algorithm is given, showing that it defines a semidecision algorithm for the validity problem in the equational theories for which it applies, yielding a decision procedure whenever the algorithm terminates.

TL;DR: The stepwise refinement technique is studied from a mathematical point of view, and a relation of correct refinement between programs is defined, based on the principle that refinement steps should be correctness preserving.

TL;DR: It is shown that the regularity problem for firing sequence sets of Petri nets is decidable and L0λ is shown to be not closed under complementation without reference to the reachability problem.

TL;DR: A large class of machines with polynomial time decidable containment and equivalence problems is exhibited, and the machines in the class accept more than the regular sets.

TL;DR: The problem considered in this paper is a simplification of one arising in the study of distributed computer systems, in which are located a large number of “resources” and aLarge number of potential users of those resources.

TL;DR: Results show that more points of access into multidimensional or tree-shaped storage can save significant time and Static, descriptional complexity (program size) can be used to obtain lower bounds on dynamic, computational complexity (such as running time).

TL;DR: Two models for very-large scale integrated (VLSI) semiconductor circuits are considered that have been developed by Thompson and by Brent and Kung and it is shown that tradeoffs can be derived from a single common complexity measure of a problem.

TL;DR: A wire-routing problem which arises commonly in the layout of circuits for very large scale integration is discussed, and an optimal algorithm which constructs it is presented.

TL;DR: A model of computation is introduced which permits the analysis of both the time and space requirements of non-oblivious programs and it is demonstrated that any algorithm for sorting n inputs which is based on comparisons of individual inputs requires time-space product proportional to n2.

TL;DR: A strong connection is established between the structural and the looking back techniques for manipulating the relative complexity of computable functions and exploring the nature of subrecursive reducibilities.

TL;DR: Two basic techniques are presented to show the decidability status of a number of problems concerning node label controlled graph grammars, mainly of graph-theoretic nature.

TL;DR: A class E of storage structures which generalizes multidimensional tapes is defined and every t( n)-time bounded Turing machine whose storage structures are in E can be simulated by a t(n) loglog t (n)/log t(N)-space bounded Turing Machine.

TL;DR: Using the Take-Grant Protection Model as an abstraction for a capability-based protection system, necessary and sufficient conditions are developed for determining the number of conspirators required to transfer authority for a given system.

TL;DR: It is proved that no left cut can be NP -hard unless the polynomial hierarchy collapses to ϵ 2 P .

TL;DR: One version of Dynamic Logic is equivalent to the infinitary logic L ω 1, ω CK but regular Dynamic logic is strictly less expressive, and the ordinals ω ω and ωπ ·2 are indistinguishable by formulas of regular Dynamic Logic.

TL;DR: A practical method is presented for extending the lookahead of LR parsers, by the addition of “reduce-arcs,” which gives a machine which is close in size to the corresponding LALR(1) machine, but is capable of making use of unbounded lookahead.

TL;DR: The formal system studied in Lipton is shown to be inadequate for Computer Science in the sense that it has a model with the following defects: finite sets may be undecidable in the model.

TL;DR: In this article, a model of a general digital system is defined and the following problem is investigated: given a synchronous polyautomaton P, construct (or transform P into) an asynchronous poly automata which preserves the capability for parallel computation of P. Two solutions to the problem are shown.

TL;DR: An algorithm is presented to find a minimal augmentation which runs in a time proportional to the product of the number of vertices and the numberof edges of the resulting graph.

TL;DR: The class of probabilistic Turing machine computations to random access machines with multiplication (but without boolean vector operations) is related, and the availability of integer division seems to play a crucial role in these results.

TL;DR: The algorithm, which is the core of a running system, is presented by illustrating successive transformations of a straightforward implementation of the classical definition of reduction in the LAMBDA-calculus.

TL;DR: It is shown that the upper bound of 2 n + 1 on the number of states of the corresponding reduced automaton can be attained for all n ⩾ 2, i.e., theupper bound 2 n - 1 is optimal.

TL;DR: Using this scheme, it is proved that the equivalence problem is decidable for two dpda's, one of which is a finite-turn or one-counter machine.

TL;DR: The present paper continues the approach of [8] focussing on the characterization of complete grammar forms, that is grammar forms which generate all’ context-free languages, and introduces the central concept of expansion spectrum.