Branched covers and matrix factorizations
| Autor: | Leuschke, Graham J., Tribone, Tim |
|---|---|
| Rok vydání: | 2021 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1112/blms.12901 |
| Popis: | Let $(S,\mathfrak n)$ be a regular local ring and $f$ a non-zero element of $\mathfrak n^2$. A theorem due to Kn\"orrer states that there are finitely many isomorphism classes of maximal Cohen-Macaulay $R=S/(f)$-modules if and only if the same is true for the double branched cover of $R$, that is, the hypersurface ring defined by $f+z^2$ in $S[[ z ]]$. We consider an analogue of this statement in the case of the hypersurface ring defined instead by $f+z^d$ for $d\ge 2$. In particular, we show that this hypersurface, which we refer to as the $d$-fold branched cover of $R$, has finite Cohen-Macaulay representation type if and only if, up to isomorphism, there are only finitely many indecomposable matrix factorizations of $f$ with $d$ factors. As a result, we give a complete list of polynomials $f$ with this property in characteristic zero. Furthermore, we show that reduced $d$-fold matrix factorizations of $f$ correspond to Ulrich modules over the $d$-fold branched cover of $R$. Comment: 17 pages, comments welcome. v2: correction to a mistake in Example 3.6 as well as other minor changes |
| Databáze: | arXiv |
| Externí odkaz: |
|