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arXiv · 0704.3565

Enumerating permutations avoiding more than three Babson - Steingr\'ımsson patterns

Antonio Bernini·Elisa Pergola
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Abstract

Not long ago, Claesson and Mansour proposed some conjectures about the enumeration of the permutations avoiding more than three Babson - Steingr\'ımsson patterns (generalized patterns of type $(1,2)$ or $(2,1)$). The avoidance of one, two or three patterns has already been considered. Here, the cases of four and five forbidden patterns are solved and the exact enumeration of the permutations avoiding them is given, confirming the conjectures of Claesson and Mansour. The approach we use can be easily extended to the cases of more than five forbidden patterns.

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Antonio Bernini, Elisa Pergola. 2007-04-26. Enumerating permutations avoiding more than three Babson - Steingr\'ımsson patterns. https://arxiv.org/abs/0704.3565

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