Enumeration of Order Ideals of a Garland

Emanuele Munarini1
1Dipartimento di Matematica Politecnico di Milano P.za Leonardo da Vinci, 32 20133 Milano, Italy

Abstract

We enumerate all order ideals of a garland, a partially ordered set which generalizes crowns and fences. Moreover, we give some bijection between the set of such ideals and the set of certain kinds of lattice paths.