The residual-intersection conjecture for powers of ideals

Let SS be a standard graded polynomial ring over an infinite field, let ISI\subset S be a homogeneous ideal generated in a single degree δ\delta with analytic spread \ell, and let JIJ\subset I be generated by 1\ell-1 general elements of degree δ\delta. Set R=S/(J:I)R=S/(J:I). The ideal J:IJ:I is a geometric (1)(\ell-1)-residual intersection of II when it is a residual intersection with the stated geometricity condition, and II is unmixed when all its associated primes have the same dimension.

Residual-intersection conjecture. If II is unmixed and J:IJ:I is a geometric (1)(\ell-1)-residual intersection of II, then, for all ρ0\rho\gg0,

IρRI^{\rho}R

is a maximal Cohen–Macaulay RR-module.

This extends the preceding theorem on asymptotic powers after residual intersection, which establishes the same conclusion under stronger hypotheses, including eventual linear presentation. The conjecture asks whether unmixedness and geometric residual-intersection hypotheses alone guarantee maximal Cohen–Macaulayness for all sufficiently high powers.

Sources & referencesView supporting material

Primary source

David Eisenbud, Craig Huneke and Bernd Ulrich, “Residual Intersections and Linear Powers”, arXiv:2001.05089 (2021).

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