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Showing papers in "Journal of Computer and System Sciences in 1993"


Journal ArticleDOI
TL;DR: A generalized model of rough sets called variable precision model (VP-model), aimed at modelling classification problems involving uncertain or imprecise information, is presented and the main concepts are introduced formally and illustrated with simple examples.

1,975 citations



Journal ArticleDOI
TL;DR: The handle-rewriting hypergraph grammars (HH Grammars) are introduced, based on the replacement of handles, i.e., of subhypergraphs consisting of one hyperedge together with its incident vertices, which can be characterized as the least solutions of certain systems of equations.

360 citations


Journal ArticleDOI
TL;DR: To what extent imprecise threshold gates (which behave unpredictably near the threshold value) can compute nontrivial functions in bounded depth and a bound is given for the permissible amount of imprecision.

241 citations


Journal ArticleDOI
TL;DR: This work gives a transparent proof of the fact that a formal language is expressible in this logic if and only if its syntactic semigroup is finite and aperiodic, and states a similar condition for the “restricted” temporal logic (RTL), obtained by discarding the ”until” operator.

102 citations


Journal ArticleDOI
TL;DR: In particular, the authors showed that subtraction is hard for the closure properties of #P, SpanP, OptP, and MidP, which is a general theory of complexity of closure properties.

95 citations


Journal ArticleDOI
TL;DR: It is shown that the cardinality of a solution to the problem can be computed from a given graph and that there is an O ( n v + n e ) algorithm for finding a solution, where n v and n e are the numbers of vertices and edges of a givengraph, respectively.

49 citations


Journal ArticleDOI
TL;DR: This work gives the first comprehensive complexity analysis of a class of potentially unbounded Petri nets defined in terms of their behavior, and argues that although neither normal nor sinkless Petrinets are strictly more powerful than persistentPetri nets, they nonetheless are both capable of modeling a more interesting class of problems.

33 citations


Journal ArticleDOI
TL;DR: This paper extends Part 1 of the paper with the same title, here, matricial iteration theories Matr(S; V) are characterized by identities involving theory operations, a star operation S → S and an omegaoperation S → V.

32 citations


Journal ArticleDOI
TL;DR: A family of probabilistic algorithms which learn binary weights for a McCulloch-Pitts neuron with inputs constrained to be binary is proposed here, the target functions being majority functions of a set literals.

25 citations


Journal ArticleDOI
TL;DR: It is demonstrated by proving that actor grammars where, in each configuration, each message has a destination, are equivalent (in a well-defined sense) to arbitrary actor Grammars.

Journal ArticleDOI
TL;DR: This paper shows that the memory element proposed in the literature can be transformed in into a soliton tree, thus turning a deterministic device into a logically equivalent strongly deterministic devices.

Journal ArticleDOI
TL;DR: This paper makes the initial steps towards a theory of parallel logic programming, i.e., parallelization without overhead, by proposing strategies that do incur an overhead, but are optimal in a sense that will be precisely defined.

Journal ArticleDOI
TL;DR: In this article, it is shown that using more flexible reduction types fails to increase the size of a degree, and this is described as a collapsing degree, where all many-one-complete sets for exponential time are indeed equivalent with respect to many one length-increasing reductions.

Journal ArticleDOI
TL;DR: The results show that, although p -cheatable, P/poly, and p -close sets all exhibit some form of polynomial time behavior, the notions of p -cheatability and p-closeness are often orthogonal.


Journal ArticleDOI
Klaus Jansen1
TL;DR: At first it is shown, that the problem of finding an assignment with minimum number of links is NP-complete, and after that it is proved that theproblem of using a given interconnection schema is NP -complete, too.

Journal ArticleDOI
TL;DR: This paper studies PLA-folding heuristics from a theoretical perspective, using the folding ratio of the heuristic to characterize its worst case behavior and shows that for arbitrary PLAs, each of theHeuristics exhibits unbounded worst-case behavior.