In this paper, we study the rank polynomial of the distributive lattice of order ideals of fences and crowns. In particular, we prove the unimodality of these polynomials, we 1nd their generating… (More)

A Lucas cube 3^ can be defined as the graph whose vertices are the binary strings of length n without either two consecutive l's or a 1 in the first and in the last position, and in which the… (More)

We consider the class of L-convex polyominoes, i.e. those polyominoes in which any two cells can be connected with an “L” shaped path in one of its four cyclic orientations. The paper proves… (More)

We study combinatorial properties of the species of scattered subsets in the case of linearly ordered sets and in the case of cycles. In particular, we study the numbers of such subsets which turn… (More)