Order Theory — Chromatic Polynomials, Chordal Graphs, Order Polynomials, Dilworth & Hall
Chromatic polynomial, chordal/interval graphs, PEO product formula, order polynomials (chain/antichain/tree/DAG/divisor lattice), MacMahon formula, Dilworth, Mirsky, Hall’s marriage theorem, Erdős–Szekeres, missile interception.