# Hasse diagram

1. (set theory) A diagram which represents a finite poset, in which nodes are elements of the poset and arrows represent the order relation between elements. Transitivity of the order relation is tacit, in other words, if $x \le y$ and $y \le z$ then no arrow is drawn from x to z, but if there is no distinct z between x and y (such that $x \le z \le y$) then an arrow is draw from x to y.