On counting n-element trellises having exactly one pair of noncomparable elements
نویسندگان
چکیده
The concept of a pseudo ordered set was introduced by Fried (see [4]). A reflexive and antisymmetric relation ⊳ on a set A is a pseudo order and the pair 〈A, ⊳ 〉 is a pseudo ordered set or a psoset. Two elements a and b are non comparable in A, written a||b, if neither a ⊳ b nor b ⊳ a holds in A. A psoset any two of whose elements are comparable is a tournament. If B is a subset of a psoset A, an element c in A is an upper bound of B if b ⊳ c for all b in B; c is the least upper bound of B if c is an upper bound of B and c ⊳ d for any upper bound d of B. The lower bound and the greatest lower bound of B are defined dually.
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عنوان ژورنال:
- Australasian J. Combinatorics
دوره 41 شماره
صفحات -
تاریخ انتشار 2008