### 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^{i}w [9] and every slender context-free language can be described by a finite union of terms of the form uv^{i}wx^{i} y [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_{1}y_{1}^{i}x_{2}y_{2} ^{i}⋯x_{n}y_{n}^{i}x_{n+1}.

Original language | English |
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Pages (from-to) | 41-47 |

Number of pages | 7 |

Journal | Fundamenta Informaticae |

Volume | 31 |

Issue number | 1 |

DOIs | |

Publication status | Published - 1997 Jul |

### Keywords

- Control sets
- Cryptosystems
- Slender languages

### ASJC Scopus subject areas

- Theoretical Computer Science
- Algebra and Number Theory
- Information Systems
- Computational Theory and Mathematics