Hasse diagram

Named after Helmut Hasse (1898–1979), though he was not the first to use them.

Hasse diagram (plural Hasse diagrams)

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 ${\displaystyle x\leq y}$ and ${\displaystyle y\leq z}$ then no arrow is drawn from x to z, but if there is no distinct z between x and y (such that ${\displaystyle x\leq z\leq y}$ ) then an arrow is draw from x to y.