On factorization forests of finite height

  • Authors:
  • Jérémie Chalopin;Hing Leung

  • Affiliations:
  • Département d'Informatique, École Normale Supérieure de Lyon, Lyon 69364, France;Department of Computer Science, New Mexico State University, Box 30001, MSC CS, Las Cruces, NM

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2004

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Abstract

Simon (Theoret. Comput. Sci. 72 (1990) 65-94) has proved that every morphism from a free semigroup to a finite semigroup S admits a Ramseyan factorization forest of height at most 9|s|. In this paper, we prove the same result of Simon with an improved bound of 7|S|. We provide a simple algorithm for constructing a factorization forest. In addition, we show that the algorithm cannot be improved significantly. We give examples of semigroup morphism such that any Ramseyan factorization forest for the morphism would require a height not less than |S|.