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Annals of Combinatorics

, Volume 8, Issue 2, pp 123–131 | Cite as

A Note on Blockers in Posets

  • Anders Björner
  • Axel Hultman
Original Paper

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.

antichain blocker partition dominance refinement blocking set Tur an 

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Copyright information

© Birkhäuser-Verlag Basel 2004

Authors and Affiliations

  1. 1.Department of MathematicsRoyal Institute of TechnologyStockholmSweden

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