### Abstract

Given two words, text T of length n and episode P of length m, the episode matching problem is to find all minimal length substrings of text T that contain episode P as a subsequence. The respective optimization problem is to find the smallest number w, s.t. text T has a subword of length w which contains episode P. In this paper, we introduce a few efficient off-line as well as on-line algorithms for the entire problem, where by on-line algorithms we mean algorithms which search from left to right consecutive text symbols only once. We present two alphabet independent algorithms which work in time O(nm). The off-line algorithm operates in O(1) additional space while the on-line algorithm pays for its property with O(m) additional space. Two other on-line algorithms have subquadratic time complexity. One of them works in time O(nm/log m) and O(m) additional space. The other one gives a time/space trade-off, i.e., it works in time O(n + s +nm log log s/ log(s/m)) when additional space is limited to O(s). Finally, we present two approximation algorithms for the optimization problem. The off-line algorithm is alphabet independent, it has superlinear time complexity O(n/ε + n log log(n/m)) and it uses only constant space. The on-line algorithm works in time O(n/ε + n) and uses space O(m). Both approximation algorithms achieve 1 + ε approximation ratio, for any e > 0.

Original language | English (US) |
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Title of host publication | Combinatorial Pattern Matching - 8th Annual Symposium, CPM 1997, Proceedings |

Editors | Alberto Apostolico, Jotun Hein, Alberto Apostolico |

Publisher | Springer Verlag |

Pages | 12-27 |

Number of pages | 16 |

ISBN (Print) | 9783540632207 |

State | Published - Jan 1 1997 |

Externally published | Yes |

Event | 8th Annual Symposium on Combinatorial Pattern Matching, CPM 1997 - Aarhus, Denmark Duration: Jun 30 1997 → Jul 2 1997 |

### Publication series

Name | Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) |
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Volume | 1264 |

ISSN (Print) | 0302-9743 |

ISSN (Electronic) | 1611-3349 |

### Conference

Conference | 8th Annual Symposium on Combinatorial Pattern Matching, CPM 1997 |
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Country | Denmark |

City | Aarhus |

Period | 6/30/97 → 7/2/97 |

### ASJC Scopus subject areas

- Theoretical Computer Science
- Computer Science(all)

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## Cite this

*Combinatorial Pattern Matching - 8th Annual Symposium, CPM 1997, Proceedings*(pp. 12-27). (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 1264). Springer Verlag.