Abstract In this paper, we introduce the notion of a connected sum K1 #Z K2 of simplicial complexes K1 and K2, as well as define a strong connected sum. Geometrically, the connected sum is motivated by Lerman’s symplectic cut applied to a toric orbifold, and algebraically, it is motivated by the connected sum of rings introduced by Ananthnarayan–Avramov–Moore [1]. We show that the Stanley–Reisn...

Let S = K[x1, . . . , xn] denote the polynomial ring in n variables over a field K with each deg xi = 1. Let ∆ be a simplicial complex on [n] = {1, . . . , n} and I∆ ⊂ S its Stanley–Reisner ideal. We write ∆e for the exterior algebraic shifted complex of ∆ and ∆c for a combinatorial shifted complex of ∆. Let βii+j(I∆) = dimK Tori(K, I∆)i+j denote the graded Betti numbers of I∆. In the present p...

Let M be a monomial ideal in the polynomial ring S = k[x1, . . . , xn] over a field k. We are interested in the problem of resolving S/M over S. The difficulty in resolving minimally is reflected in the fact that the homology of arbitrary simplicial complexes can be encoded (via the Stanley-Reisner correspondence) into the multigraded Betti numbers of S/M , [St]. In particular, the minimal free...

Associated to a simple undirected graph G is a simplicial complex ∆G whose faces correspond to the independent sets of G. We call a graph G shellable if ∆G is a shellable simplicial complex in the non-pure sense of Björner-Wachs. We are then interested in determining what families of graphs have the property that G is shellable. We show that all chordal graphs are shellable. Furthermore, we cla...

Steingrı́msson (2001) showed that the chromatic polynomial of a graph is the Hilbert function of a relative StanleyReisner ideal. We approach this result from the point of view of Ehrhart theory and give a sufficient criterion for when the Ehrhart polynomial of a given relative polytopal complex is a Hilbert function in Steingrı́msson’s sense. We use this result to establish that the modular and ...

It is shown in this paper how a solution for a combinatorial problem obtained from applying the greedy algorithm is guaranteed to be optimal for those instances of the problem that, under an appropriate algebraic representation, satisfy the Cohen-Macaulay property known for rings and modules in Commutative Algebra. The choice of representation for the instances of a given combinatorial problem ...

We prove that certain class of Stanley–Reisner rings having sufficiently large multiplicities are Cohen–Macaulay using Alexander duality.

We give a purely combinatorial characterization of complete Stanley-Reisner rings having a principally generated (equivalently, finitely generated) Cartier algebra.