Fundamenta Informaticae - Volume 26, issue 1

Authors: Biswas, Ranjit

Article Type: Research Article

Abstract: We define level subsets of an i–v fuzzy subset of a set, level subgroups of a group and prove some propositions about level subgroups.

Keywords: Fuzzy sets, i–v fuzzy sets, level subsets, i–v fuzzy subgroups, level subgroups

DOI: 10.3233/FI-1996-2611

Citation: Fundamenta Informaticae, vol. 26, no. 1, pp. 1-9, 1996

Authors: Menezes, P. Blauth | Costa, J. Félix

Article Type: Research Article

Abstract: In “Petti nets are Monoids” by Meseguer and Montanari, categories for Petri nets with and without markings are introduced, where the categorical product and coproduct express the joint behavior of nets. However, this framework lacks structure in the sense that there is no categorical technique to define a composition of nets satisfying some given synchronization specification. In this paper, a synchronization operation is proposed which is a functor induced by some given synchronization prescription at the transition level. Moreover, since this operation is also able to represent the asynchronous composition, the fact that some categories of Petri nets lack coproducts …(asynchronous composition) is not anymore a restriction for interaction semantics. Show more

DOI: 10.3233/FI-1996-2612

Citation: Fundamenta Informaticae, vol. 26, no. 1, pp. 11-22, 1996

Authors: Spilker, Heike | Wätjen, Dietmar

Article Type: Research Article

Abstract: In this paper we shall prove that is is undecidable whether the intersection of two k-limited 0L languages is empty, finite, regular, context-free or a k-limited language, whether the language generated by a context-free grammar is a k-limited 0L language or whether a klT0L language can be generated by a context-free grammar. Furthermore, it is undecidable whether the union of two k-limited 0L languages is such a language again.

DOI: 10.3233/FI-1996-2613

Citation: Fundamenta Informaticae, vol. 26, no. 1, pp. 23-30, 1996

Authors: Rishe, Naphtali

Article Type: Research Article

Abstract: We propose a language which can express every computable query. The language is syntactically based on the first-order predicate calculus, but semantically is interpreted as post-conditions, unlike the customary calculus query languages. The language has a capability to restrict itself to reasonable queries, accepting criteria of reasonability as a parameter.

DOI: 10.3233/FI-1996-2614

Citation: Fundamenta Informaticae, vol. 26, no. 1, pp. 31-57, 1996

Authors: Boldi, Paolo

Article Type: Research Article

Abstract: In the field of abstract measurement theory, semiorders have assumed an especially important role as a natural setting for expressing the comparative relations among the magnitudes of measurands. If we assume in addition that our measuring scale is bounded below, which happens in many important cases, we get an interesting class of semiorders, the strongly noetherian ones. In this work, we study some combinatorial and order-theoretic properties of strongly noetherian semiorders, with a particular regard to the structure of maximal chains and antichains (called lines and cuts in the present paper). We see that the cuts determine a sort of …dynamics in the semiorder, which may be described as a linear order on the cuts themselves; from this linear order one can extract the main properties of the original semiorder, whose elements are represented as closed intervals of cuts. Moreover, “continuity” properties such as K-density and coherence have a natural description in term of simple cut properties; as a corollary, we obtain that K-density is equivalent to N-freeness in strongly noetherian semiorders. Show more

DOI: 10.3233/FI-1996-2615

Citation: Fundamenta Informaticae, vol. 26, no. 1, pp. 59-80, 1996

Authors: Szalas, Andrzej

Article Type: Research Article

Abstract: In the current paper we present a powerful technique of obtaining natural deduction proof systems for first-order fixpoint logics. The term fixpoint logics refers collectively to a class of logics consisting of modal logics with modalities definable at meta-level by fixpoint equations on formulas. The class was found very interesting as it contains most logics of programs with e.g. dynamic logic, temporal logic and the μ-calculus among them. In this paper we present a technique that allows us to derive automatically natural deduction systems for modal logics from fixpoint equations defining the modalities.

DOI: 10.3233/FI-1996-2616

Citation: Fundamenta Informaticae, vol. 26, no. 1, pp. 81-94, 1996

Authors: Hirshfeld, Yoram

Article Type: Research Article

Abstract: The shuffle operator models communication free concurrency and has little expressive power (it does not produce new languages when added to regular expressions). Decidability problems for languages involving this operation were previously tackled but remained unsolved (except for a weak conjecture). We prove that language equivalence is undecidable even for a very restricted class of expressions involving the shuffle operator. This also re-proves that language equivalence is undecidable for Basic Parallel Processes.

DOI: 10.3233/FI-1996-2617

Citation: Fundamenta Informaticae, vol. 26, no. 1, pp. 95-102, 1996