On a Hierarchy of Slender Languages Based on Control Sets

  • Authors:

  • Takeshi Koshiba

  • Affiliations:

  • High Performance Computing Research Center, Fujitsu Laboratoires Ltd., 4-1-1 Kamikodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa 211, Japan. e-mail: koshiba@flab.fujitsu.co.jp

  • Venue:
  • Fundamenta Informaticae
  • Year:
  • 1997

Quantified Score

Hi-index 0.00

Visualization

Abstract

We study slender context-sensitive languages, i.e., those containing at most a constant number of words of each length. Recently, it was proved that every slender regular language can be described by a finite union of terms of the form uv iw [9] and every slender context-free language can be described by a finite union of terms of the form uv iwx iy [4, 10]. We show a hierarchy of slender languages which is properly contained in the family of context-sensitive languages and which starts with the family of slender context-free languages, or slender regular languages. Each slender context-sensitive language in the hierarchy can be described by a finite union of terms of the form x 1y i 1x 2y i 2 ··· x ny i nx n+1.