Hochster's small Cohen–Macaulay conjecture

Let (R,m)(R,\mathfrak{m}) be a complete local ring. A small Cohen–Macaulay module over RR is a nonzero finitely generated RR-module SS such that depth(S)=dim(R)\operatorname{depth}(S)=\dim(R). Hochster's small Cohen–Macaulay conjecture. Every complete local ring admits a small Cohen–Macaulay module. The conjecture asks whether finite Cohen–Macaulay modules exist for all complete local rings; the paper's abstract indicates that, in mixed characteristic and dimension at least four, there are normal local domains with no small Cohen–Macaulay algebra, while still admitting small Cohen–Macaulay modules.

Sources & referencesView supporting material

Primary source

Kazuma Shimomoto and Ehsan Tavanfar, “On local rings without small Cohen-Macaulay algebras in mixed characteristic”, arXiv:2109.12700 (2024).

Additional references

4 papers in this index state this conjecture (2010–2021). The statement above is taken from the most recent of them; the others are arXiv:1310.0389, arXiv:1203.0907, arXiv:1005.3275.

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