Directed animals, forests and permutations

In this paper, we illustrate a method to enumerate two-dimensional directed animals, with compact sources, on both the square and the triangular lattice. We give a recursive description of these structures from which we deduce their generating function, according to various parameters: the area, the right half-width and the number of compact sources. We determine the average number of compact sources in both lattices. Referring to single-source animals on the square lattice, we show the bijections connecting them to the forests of 1

• Type: Journal
• Year: 1999
• Where: DM
• Authors: Elena Barcucci, Alberto Del Lungo, Elisa Pergola, Renzo Pinzani
• Keywords: Compact Sources, DM 1999, Single-source Animals, Triangular Lattice