State complexity of union and intersection of finite languages

Yo Sub Han, Kai Salomaa

Research output: Contribution to journalArticle

20 Citations (Scopus)


We investigate the state complexity of union and intersection for finite languages. Note that the problem of obtaining the tight bounds for both operations was open. First we compute upper bounds using structural properties of minimal deterministic finite-state automata for finite languages. Then, we show that the upper bounds are tight if we have a variable sized alphabet that can depend on the size of input deterministic finite-state automata. In addition, we prove that the upper bounds are unreachable for any fixed sized alphabet.

Original languageEnglish
Pages (from-to)581-595
Number of pages15
JournalInternational Journal of Foundations of Computer Science
Issue number3
Publication statusPublished - 2008 Jun 1


All Science Journal Classification (ASJC) codes

  • Computer Science (miscellaneous)

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