The conjectural extension of the module-variety reconstruction theorem

Let AA and BB be graded Cohen–Macaulay kk-algebras that are isomorphic as graded SS-modules. In the notation of Theorem 1, let VV be the common finite-dimensional graded kk-vector space such that AA and BB are isomorphic to SkVS\otimes_k V as graded SS-modules, and consider their graded module varieties RepS(A,V)(k)\mathrm{Rep}_S(A,V)(k) and RepS(B,V)(k)\mathrm{Rep}_S(B,V)(k).

Conjecture. Theorem 1 would remain valid without any assumptions on the algebras AA and BB other than their being isomorphic as graded SS-modules; equivalently, the conditions in that theorem would still be equivalent without assuming that BB is an integral domain or Gorenstein on the punctured spectrum.

The preceding theorem uses the additional hypotheses on BB only to prove injectivity of the natural map from BB to the graded endomorphism algebra of the corresponding module. The conjecture asks whether the reconstruction result nevertheless holds for arbitrary graded Cohen–Macaulay algebras with the stated graded SS-module isomorphism.

Sources & referencesView supporting material

Primary source

Naoya Hiramatsu, “Geometry of varieties for graded maximal Cohen–Macaulay modules”, arXiv:2002.11294 (2020).

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