Obtaining shorter regular expressions from finite-state automata

Yo Sub Han, Derick Wood

Research output: Contribution to journalArticle

31 Citations (Scopus)


We consider the use of state elimination to construct shorter regular expressions from finite-state automata (FAs). Although state elimination is an intuitive method for computing regular expressions from FAs, the resulting regular expressions are often very long and complicated. We examine the minimization of FAs to obtain shorter expressions first. Then, we introduce vertical chopping based on bridge states and horizontal chopping based on the structural properties of given FAs. We prove that we should not eliminate bridge states until we eliminate all non-bridge states to obtain shorter regular expressions. In addition, we suggest heuristics for state elimination that leads to shorter regular expressions based on vertical chopping and horizontal chopping.

Original languageEnglish
Pages (from-to)110-120
Number of pages11
JournalTheoretical Computer Science
Issue number1-3
Publication statusPublished - 2007 Feb 12

All Science Journal Classification (ASJC) codes

  • Theoretical Computer Science
  • Computer Science(all)

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