COMPLETELY DISJUNCTIVE LANGUAGES

Authors

  • S. S. YU
  • S. W. JIANG
  • H. J. SHYR

Abstract

A language over a finite alphabet X is called disjunctive if the principal congruence PL determined by L is the equality. A dense language is a language which has non-empty intersection with any two-sided ideal of the free monoid X* generated by the alphabet X. We call an infinite language L completely disjunctive (completely dense) if every infinite subset of L is disjunctive (dense). For a language L, if every dense subset of L is disjunctive, then we call L quasi-completely disjunctive. In this paper, (for the case IXI ≥ 2) we show that every completely disjunctive language is completely dense and conversely. Characterizations of completely disjunctive languages and quasi-completely disjunctive languages were obtained. We also discuss some operations on the families of languages.

How to Cite

YU, S. S., JIANG, S. W., SHYR, H. J. (1991) “COMPLETELY DISJUNCTIVE LANGUAGES”, Periodica Polytechnica Transportation Engineering, 19(1-2), pp. 101–110.

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Articles