# Discrete Mathematics & Theoretical Computer Science

## Volume 7 n° 1 (2005), pp. 71-74

author: | M. D. Atkinson |
---|---|

title: | Some equinumerous pattern-avoiding classes of permutations |

keywords: | Permutations, patterns, enumeration |

abstract: | Suppose that p,q,r,s are non-negative integers with m=p+q+r+s. The class X(p,q,r,s) of permutations that contain no pattern of the form αβγ where |α|=r, |γ|=s and β is any arrangement of {1,2,…,p}∪{m-q+1, m-q+2, …,m} is considered. A recurrence relation to enumerate the permutations of X(p,q,r,s) is established. The method of proof also shows that X(p,q,r,s)=X(p,q,1,0)X(1,0,r,s) in the sense of permutational composition.2000 MATHEMATICS SUBJECT CLASSIFICATION: 05A05 If your browser does not display the abstract correctly (because of the different mathematical symbols) you can look it up in the PostScript or PDF files. |

reference: | M. D. Atkinson (2005),
Some equinumerous pattern-avoiding classes of permutations,
Discrete Mathematics and Theoretical Computer Science 7, pp. 71-74 |

bibtex: | For a corresponding BibTeX entry, please consider our BibTeX-file. |

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