Showing papers in "Journal of Computer and System Sciences in 1986"

TL;DR: A new class of finite automata on infinite trees for which the emptiness problem can be solved in polynomial time is presented, and exponential decision procedures for modal logics of programs are given.

TL;DR: This work proposes a very general mathematical model for physical noise sources: the semi-random source, and shows how to convert the output of such sources into quasi-random sequences, which are indistinguishable from truly random ones in a strong sense.

TL;DR: It is shown that every 2-connected triangulated planar graph with n vertices has a simple cycle C of length at most 2√2 · n which separates the interior vertices A from the exterior vertices B such that neither A nor B contain more than 2 3n vertices.

TL;DR: The theory of real closed fields can be decided in exponential space or parallel exponential time and in fixed dimension, the theory can be decisions in NC.

TL;DR: A key feature of the model is an algebraic query language allowing data restructuring, and a natural connection between instances in this model, and relational database instances satisfying the Universal Relation Scheme Assumption is investigated.

TL;DR: This work considers rewrite rules with conditions, such as they arise, e.g., from algebraic specifications with positive conditional equations, for left-linear, nonambiguous TRSs, and proves confluence results and termination results for some well-known reduction strategies.

TL;DR: Algorithms for concurrent operations (i.e., searches, insertions, and deletions) on B∗-trees are presented and improvement is the ability to compress the tree when some nodes become too sparse as a result of some deleting.

TL;DR: This paper analyzes the use of Armstrong relations in database design with functional dependencies, and shows how they and the usual representation of dependencies can be used together.

TL;DR: The logarithmic lower bound on communication complexity is applied to obtain an Ω(n log n) bound on the time of 1-tape unbounded error probabilistic Turing machines, believed to be the first nontrivial lower bound obtained for such machines.

TL;DR: A one-dimensional array of cellular automata on which arbitrarily large computations can be implemented reliably, even though each automaton at each step makes an error with some constant probability, leads to the refutation of the positive probability conjecture.

TL;DR: It is shown that if the authors restrict logical clocks to running within some linear functions of real time, then clock synchronization is impossible without authentication when one-third or more of the processors are faulty.

TL;DR: McNaughton was the first to consider the case where the set of formulas is restricted to first-order, that is, when set-variables are ignored and it was proved that the languages defined in this way are precisely the star-free languages.

TL;DR: New simple hardness proofs for certain propositional logics are obtained as an application of the computational complexity of problems of existence of winning strategies in domino tilings.

TL;DR: A data structure is introduced that requires only one pointer for every k data values and supports searches in O(log n) time and insertions and deletions in K+log n time while using only the storage needed for the data.

TL;DR: The membership problem for fixed context-sensitive languages is polynomial if the right hand side of every production is strictly longer than the left hand side.

TL;DR: It is shown that the Boundedness Problem (BP), for VASS(k, l, n), can be solved in O((l + log n)∗2c∗k∗logk) nondeterministic space, and that the BP is PSPACE-complete for four-dimensional VASSs, and NP-hard for two-dimensionalVASSs.

TL;DR: It is proved that quasi-varieties are exactly classes of models definable by abstract infinitary conditional equations and inequations, and “syntactic” characterizations of abstract algebraic institutions which guarantee the existence of reachable initial models for any consistent set of axioms are obtained.

TL;DR: An algorithm is described whose running time is O(n(log2 nlog log n)+k, the first solution with a time bound linear in the size of the output, and a new hierarchical strategy for dealing with segments without reducing the dimensionality of the problem is introduced.

TL;DR: This work describes an approximation algorithm for query evaluation that enables one to implement a logical database on the top of a standard database management system.

TL;DR: It is shown that no 2-way probabilistic finite automaton that runs in exp( o ( n )) expected time recognizes { a m b m : m ⩾ 1} with probability of error bounded away from 1 2 .

TL;DR: The expressive power of PDs is investigated, and it is shown that partition semantics justify a number of variants of an assumption commonly used in database theory, namely the weak instance assumption.

TL;DR: It is shown that, if the bipartite graphs satisfy suitable chordality properties, the Steiner problem may be solved in polynomial time and correspond to the concepts of acyclicity that are usually considered in the relational model of data.

TL;DR: It is proved that computing majority on depth d monotone circuits requires exp Ω(n 1 (d−1 ) ) size, which implies exponential lower bounds for other functions, such as testing connectivity and detecting cliques in graphs.

TL;DR: The Paterson-Wegman unification algorithm is investigated and the combination of pre-processor, core algorithm, and post-processor is still a linear algorithm (with respect to the sum of nodes and edges in the input graph).

TL;DR: The cover computed by the algorithm is characterized as a minimum of a certain fixed point equation, and is in general a better cover than might be computed by iteration methods (which can compute fixed point covers which are not minimal).

TL;DR: This work proves a new result of this type by presenting an effectively defined Boolean function whose complexity in depth-restricted one-time-only branching programs is exponential while its complexity even in width-2 branching program is polynomial.

TL;DR: It is shown that, given an arbitrary NLC grammar G generating the language L(G) of bounded degree, one can effectively compute the maximum integer which appears as the degree of a graph in L( G) .

TL;DR: A new notion of multiversion serializability (MVSR) based on conflicts (MMVCSR) is introduced, and its relation with the well known single version conflict serialIZability (CSR).

TL;DR: An algorithm is presented, requiring O ( n ) computation time, which moves an arm confined in a circular region to any reachable configuration in O (n ) moves, and an algorithm that computes all the regions reachable by the joints of such an arm is given.

TL;DR: In the remaining section the authors shall see how this unique model of Milner’s can be recovered from the above fully abstract submodel in a simple way.