The weak separation in higher dimensions

Abstract: For an odd integer $r>0$ and an integer $n>r$, we introduce a notion of weakly $r$-separated collections of subsets of $[n]={1,2,\ldots,n}$. When $r=1$, this corresponds to the concept of weak separation introduced by Leclerc and Zelevinsky. In this paper, extending results due to Leclerc-Zelevinsky, we develop a geometric approach to establish a number of nice combinatorial properties of maximal weakly r-separated collections. As a supplement, we also discuss an analogous concept when $r$ is even.