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arXiv · 2309.05612

Flag-Shaped Blockers of 123-Avoiding Permutation Matrices

Megan Bennett·Lei Cao
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Abstract

A blocker of $123$-avoiding permutation matrices refers to the set of zeros contained within an $n\times n$ $123$-forcing matrix. Recently, Brualdi and Cao provided a characterization of all minimal blockers, which are blockers with a cardinality of $n$. Building upon their work, a new type of blocker, flag-shaped blockers, which can be seen as a generalization of the $L$-shaped blockers defined by Brualdi and Cao, are introduced. It is demonstrated that all flag-shaped blockers are minimum blockers. The possible cardinalities of flag-shaped blockers are also determined, and the dimensions of subpolytopes that are defined by flag-shaped blockers are examined.

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Megan Bennett, Lei Cao. 2023-09-11. Flag-Shaped Blockers of 123-Avoiding Permutation Matrices. https://arxiv.org/abs/2309.05612

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