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The fine structure of 321 avoiding permutations

Michael H. Albert
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Abstract

Bivariate generating functions for various subsets of the class of permutations containing no descending sequence of length three or more are determined. The notion of absolute indecomposability of a permutation is introduced, and used in enumerating permutations which have a block structure avoiding 321 and whose blocks also have such structure (recursively). Generalizations of these results are discussed.

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Michael H. Albert. 2015-08-05. The fine structure of 321 avoiding permutations. https://arxiv.org/abs/math/0212163

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