In this paper we study topological properties of the poset of injective words and the lattice of classical non-crossing partitions. Specifically, it is shown that after the removal of the bottom and top elements (if existent) these posets are doubly Cohen-Macaulay. This extends the well-known result that those posets are shellable. Both results rely on a new poset fiber theorem, for doubly homo...

In 2001, the notion of a fuzzy poset defined on a set X via a triplet (L,G, I) of functions with domain X ×X and range [0, 1] satisfying a special condition L+G+ I = 1 is introduced by J. Negger and Hee Sik Kim, where L is the ‘less than’ function, G is the ‘greater than’ function, and I is the ‘incomparable to’ function. Using this approach, we are able to define a special class of fuzzy poset...

A special case of the Generalized Baues Conjecture states that the order complex of the Baues poset of an acyclic vector connguration A (the Baues complex of A) is homotopy equivalent to a sphere of dimension equal to the corank of A minus one. The Baues poset of A is the set of proper polyhedral subdivisions of A ordered by reenement. Recently, Santos has found a counterexample in corank 317 t...

We show that the order complex of poset nonempty intervals, ordered by inclusion, is a Tchebyshev triangulation original poset. Besides studying properties this transformation, we dual type B permutohedron combinatorially equivalent to suspension intervals Boolean algebra (with minimum and maximum elements removed).

New q-analogs of Stirling numbers of the second kind(and the first kined) are derived from a poset on [2k] using Stanley’s P -partition theory [?]. We also generalize to the poset on the set [rk].