The Involutory Dimension of Involution Posets

The involutory dimension, if it exists, of an involution poset P := (P,≤,′ ) is the minimum cardinality of a family of linear extensions of ≤, involutory with respect to ′, whose intersection is the ordering ≤. We show that the involutory dimension of an involution poset exists iff any pair of isotropic elements are orthogonal. Some characterizations of the involutory dimension of such posets are given. We study prime order ideals in involution posets and use them to generate involutory linear extensions of the partial ordering on orthoposets. We prove several of the standard results in the theory of the order dimension of posets for the involutory dimension of involution posets. For example, we show that the involutory dimension of a finite orthoposet does not exceed the cardinality of an antichain of maximal cardinality. We illustrate the fact that the order dimension of an orthoposet may be different from the involutory dimension. Mathematics Subject Classifications (2000): 03G12, 06A06, 06A07.