Topic
Formal language
About: Formal language is a research topic. Over the lifetime, 5763 publications have been published within this topic receiving 154114 citations.
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ARCO1
TL;DR: It is shown that, for any positive integer n, only finitely many words can occur twice, at distance n, in a C ∞ -word, which solves the conjecture of Păun, on the Kolakoski sequence.
29 citations
TL;DR: In this article, it was shown that the splicing operation can give rise to different subclasses of regular languages, when a finite set of rules is iterated on a set of axioms.
29 citations
01 Jan 2007
29 citations
24 Oct 1992
TL;DR: In this article, the authors provide a characterization for the class of queries that can be expressed in database query languages that have the ability to create new domain elements and motivate this term by establishing a close correspondence between object creation and the construction of hereditarily finite sets.
Abstract: Recently, various database query languages have been considered that have the ability to create new domain elements. These languages, however, are not complete in the sense of Abiteboul and Kanellakis (1989). They provide a precise characterization for the class of queries that can be expressed in these languages. They call this class the constructive queries and motivate this term by establishing a close correspondence between object creation and the construction of hereditarily finite sets. >
29 citations
TL;DR: The equivalence problem is shown to be solvable for derivation languages and Hierarchy and closure properties of these languages are considered.
Abstract: A derivation language associated with a context-free grammar is the set of all terminating derivations. Hierarchy and closure properties of these languages are considered. In addition to the formerly known solvability of the emptiness and finiteness problems the equivalence problem is shown to be solvable for derivation languages.
29 citations