Minimal free resolutions of monomial ideals and of toric rings are supported on posets

Clark, Timothy; Tchernev, Alexandre

doi:10.1090/tran/7614

Minimal free resolutions of monomial ideals and of toric rings are supported on posets
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by Timothy B. P. Clark and Alexandre B. Tchernev PDF

Trans. Amer. Math. Soc. 371 (2019), 3995-4027 Request permission

Abstract:

We introduce the notion of a resolution supported on a poset. When the poset is a CW-poset, i.e., the face poset of a regular CW-complex, we recover the notion of cellular resolution as introduced by Bayer and Sturmfels. Work of Reiner and Welker, and of Velasco, has shown that there are monomial ideals whose minimal free resolutions are not cellular, hence cannot be supported on any CW-poset. We show that for any monomial ideal there is a homology CW-poset that supports a minimal free resolution of the ideal. This allows one to extend to every minimal resolution, essentially verbatim, techniques initially developed to study cellular resolutions. As two demonstrations of this process, we show that minimal resolutions of toric rings are supported on what we call toric hcw-posets, and, generalizing results of Miller and Sturmfels, we prove a fundamental relationship between Artinianizations and Alexander duality for monomial ideals.

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