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A note on blockers in posets

Anders Björner·Axel Hultman
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Abstract

The blocker $A^{*}$ of an antichain $A$ in a finite poset $P$ is the set of elements minimal with the property of having with each member of $A$ a common predecessor. The following is done: 1. The posets $P$ for which $A^{**}=A$ for all antichains are characterized. 2. The blocker $A^*$ of a symmetric antichain in the partition lattice is characterized. 3. Connections with the question of finding minimal size blocking sets for certain set families are discussed.

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Anders Björner, Axel Hultman. 2004-03-04. A note on blockers in posets. https://arxiv.org/abs/math/0403094

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