Gallery of Posets


Here is a small gallery of posets produced by the package Posets.nb.




This is an diagram showing configurations in the "chip-firing" posets studied by Bjorner, Lovasz, and Shor (add reference). Starting with a stack of eight chips, one generates new configurations by removing two chips from a pile and distributing them to the two adjacent positions.








This is the lattice of subsets of a 5-elements set (and of course it can also be viewed as a projection of the 2-skeleton of a 5-dimensional cube).












This is a diagram of the symmetric group S_5, consisting of all permutations of a 5-element set, ordered by the "weak" order. It may also be viewed as a diagram of the Cayley graph of S_5. The highlighted elements are the Andre (alternating) permutations. (E. Hunsicker, 1992)









This is the strong order on S_4 (also known as the Bruhat order).














This is the bottom 6 levels of an example of a Young-Fibonacci lattice, introduced by Richard Stanley.


















I will be expanding this collection. If produce some other interesting examples with my package, please send them to me (cgreene@haverford.edu) and I will add them to this collection.