# a 29 Integers 9 ( 2009 ) , 353 - 374 Combinatorial Properties of the Antichains Of
نویسنده
چکیده
In this paper we study some combinatorial properties of the antichains of a garland, or double fence. Specifically, we encode the order ideals and the antichains in terms of words of a regular language, we obtain several enumerative properties (such as generating series, recurrences and explicit formulae), we consider some statistics leading to Riordan matrices, we study the relations between the lattice of ideals and the semilattice of antichains, and finally we give a combinatorial interpretation of the antichains as lattice paths with no peaks and no valleys.
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