The open world assumption in ontologies representing knowledge may assign deficient (imprecise) meaning for ontology concepts which are language adjectives referring the meaning of classes of objects (individuals). The interpretation of an imprecise (vague) concept is by three subsets of individuals. The first subset of individuals surely belongs to the vague concept, the second subset of indiv...

A regular language is called union-free if it can be represented by a regular expression that does not contain the union operation. Every regular language can be decomposed into a union of a finite number of union-free languages (the so-called union-free decomposition). We call the number of components in the minimal union-free decomposition of a regular language the union width of the regular ...

The notion of vague ideals in pseudo MV-algebras is introduced,and several properties are investigated. Conditions for a vague set to be avague ideal are provided. Conditions for a vague ideal to be implicative aregiven. Characterizations of (implicative, prime) vague ideals are discussed.The smallest vague ideal containing a given vague set is established. Primeand implicative extension proper...

A new solution is offered for the ancient ’sorites’ paradox of vagueness. The sorites paradox arises if it is assumed that if two objects are indistinguishable, then a vague predicate (e.g., large, or small) can never distinguish between them. The proposed solution to the paradox depends on a systematic ambiguity that is displayed by vague predicates as well as vague relations (e.g., the relati...

In this paper we consider two questions. First we consider whether every pattern language which is regular can be generated by a regular pattern. We show that this is indeed the case for extended (erasing) pattern languages if alphabet size is at least four. In all other cases, we show that there are patterns generating a regular language which cannot be generated by a regular pattern. Next we ...

In formal language theory, we are mainly interested in the natural language computational aspects of ω-languages. Therefore in this respect it is convenient to consider fuzzy ω-languages. In this paper, we introduce two subclasses of fuzzy regular ω-languages called fuzzy n-local ω-languages and Buchi fuzzy n-local ω-languages, and give some closure properties for those subclasses. We define a ...

One important characteristic of distributed database management systems (DBMS) is that due to network or machine failure the environment may become partitioned into sub-environments that cannot communicate with each other. However, there are various application areas where the individual sub-environments should remain operable even in such situations [2, 5]. In particular queries to the databas...