Sergi Elizalde ; Peter R. W. McNamara
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On intervals of the consecutive pattern poset
dmtcs:6380 -
Discrete Mathematics & Theoretical Computer Science,
April 22, 2020,
DMTCS Proceedings, 28th International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC 2016)
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https://doi.org/10.46298/dmtcs.6380
On intervals of the consecutive pattern posetArticle
Authors: Sergi Elizalde 1; Peter R. W. McNamara
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Sergi Elizalde;Peter R. W. McNamara
1 Department of Mathematics [Dartmouth]
The consecutive pattern poset is the infinite partially ordered set of all permutations where σ ≤ τ if τ has a subsequence of adjacent entries in the same relative order as the entries of σ. We study the structure of the intervals in this poset from topological, poset-theoretic, and enumerative perspectives. In particular, we prove that all intervals are rank-unimodal and strongly Sperner, and we characterize disconnected and shellable intervals. We also show that most intervals are not shellable and have Mo ̈bius function equal to zero.