The face vector of a half-open hypersimplex

Abstract

The half-open hypersimplex $\Delta'_{n,k}$ consists of those $x = (x_{1}, \ldots, x_{n}) \in[0,1]^n$ with $k-1<x_1+\cdots+x_n\le k$, where $0 < k \leq n$. The $f$-vector of a half-open hypersimplex and related generating functions are explicitly studied.