Let R be a polynomial ring over a field of dimension n. Let m be the maximal homogeneous ideal of R. Let I be a complete intersection homogeneous ideal of R minimally generated by polynomials of degrees d1, d2, . . . , dn. F. S. Macaulay showed that for all integers i = 0, 1, . . . , δ + 1, I : m = I + m where δ = d1 + d2 + . . .+ dn − n. We provide a modern proof of a generalization of this re...

We introduce the notions of depth and of when a local ring (or module over a local ring) is “S2”. These notions are found in most books on commutative algebra, see for example [Mat89, Section 16] or [Eis95, Section 18]. Another excellent book that is focussed on these ideas is [BH93]. We won’t be focussing on the commutative algebra, but one should be aware, at the very least, that this backgro...

A new \compressed straight" basis for the polynomial ring Z[ti;j ] is constructed. This basis is then employed to study the lattice of representations generated by the representations associated with row-convex shapes under the operations of intersection and linear span. Applications to ascertaining the Cohen-Macaulay property for rings associated to elements of this lattice are also given.

In a local Cohen-Macaulay ring (A, m), we study the Hilbert function of an m-primary ideal I whose reduction number is two. It continuous work papers Huneke, Ooishi, Sally, and Goto-Nishida-Ozeki. With some conditions, show inequality e1(I) ? e0(I) ? ?A(A/I) + e2(I) coefficients, which converse Sally Itoh. We also relations between coefficients depth associated graded ring.

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...

We provide a formula to compute the big Cohen–Macaulay test ideal for triples ((R,?),????t) where R is mixed characteristic toric ring and ???? monomial ideal. Of particular interest that this result consistent with formulas ideals in positive multiplier zero.

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

For a polynomial ring R = k[x1, ..., xn], we present a method to compute the characteristic cycle of the localization Rf for any nonzero polynomial f ∈ R that avoids a direct computation of Rf as a D-module. Based on this approach, we develop an algorithm for computing the characteristic cycle of the local cohomology modules H I (R) for any ideal I ⊆ R using the Čech complex. The algorithm, in ...

We show that the algebraic invariants multiplicity and depth of a graded ideal in the polynomial ring are closely connected to the fan structure of its generic tropical variety in the constant coefficient case. Generically the multiplicity of the ideal is shown to correspond directly to a natural definition of multiplicity of cones of tropical varieties. Moreover, we can recover information on ...

Let (R,m) be a commutative Noetherian local ring. Suppose that M and N are finitely generated modules over R such that M has finite projective dimension and such that TorRi (M,N) = 0 for all i > 0. The main result of this note gives a condition on M which is necessary and sufficient for the tensor product of M and N to be a Cohen–Macaulay module over R, provided N is itself a Cohen–Macaulay mod...