Revisiting Generalizations of the Dehn--Sommerville Relations

Abstract: We revisit several known versions of the Dehn--Sommerville relations in the context of: homology manifolds, semi-Eulerian complexes, general simplicial complexes, balanced semi-Eulerian complexes and general completely balanced complexes. In addition, we present Dehn--Sommerville relations for reciprocal complexes and general balanced simplicial complexes; which slightly generalize some of the previous results. Our proofs are uniform, and are based on two simple evaluations of the $\tilde h$-polynomial: one that recovers the $\tilde f$-polynomial, and one that counts faces according to certain multiplicities.