منابع مشابه
On the Ehrenfeucht Conjecture for DOL Languages
— Ehrenfeucht conjectured that each language L over a finite alphabet E possesses a test set, that is a finite subset F of L such that every two morphisms on E* agreeing on each string in F also agree on each string in L. We introducé the notion of déviation of a string with respect to a language and use it to give a sufficient condition for the existence of such a test set. Moreover, we prove ...
متن کاملOntological Blending in DOL
We introduce ontological blending as a method for combining ontologies. Compared with existing combination techniques that aim at integrating or assimilating categories and relations of thematically related ontologies, blending aims at creatively generating (new) categories and ontological definitions; this is done on the basis of input ontologies whose domains are thematically distinct but who...
متن کاملThe Computational Complexity of Universality Problems for Prefixes, Suffixes, Factors, and Subwords of Regular Languages
In this paper we consider the computational complexity of the following problems: given a DFA or NFA representing a regular language L over a finite alphabet Σ, is the set of all prefixes (resp., suffixes, factors, subwords) of all words of L equal to Σ? In the case of testing universality for factors of languages represented by DFA’s, we find an interesting connection to Černý’s conjecture on ...
متن کاملOn the state complexity of closures and interiors of regular languages with subwords and superwords
The downward and upward closures of a regular language L are obtained by collecting all the subwords and superwords of its elements, respectively. The downward and upward interiors of L are obtained dually by collecting words having all their subwords and superwords in L, respectively. We provide lower and upper bounds on the size of the smallest automata recognizing these closures and interior...
متن کاملOn the State Complexity of Closures and Interiors of Regular Languages with Subwords
We study the closure of regular languages by taking subwords or superwords, provide exact state complexity in the case of unbounded alphabets, and prove new lower bounds in the case of languages over a two-letter alphabet. We also consider the dual interior sets, for which the nondeterministic state complexity has a doubly-exponential upper bound and for which we prove matching doublyexponentia...
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ژورنال
عنوان ژورنال: Information and Control
سال: 1983
ISSN: 0019-9958
DOI: 10.1016/s0019-9958(83)80028-x