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Stability of CI-dimension under iteration of a local endomorphism

Establish whether, for a local ring endomorphism φ: R → R, finiteness of the complete intersection dimension cid_R(R_φ) implies finiteness of cid_R(R_{φ^n}) for every positive integer n, where R_{φ^n} denotes R regarded as an R-module via the n-th iterate of φ.

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Background

The paper proves complete intersection criteria assuming finiteness of CI-dimension for some iterate φn, but it notes that connecting these conditions to Majadas’ approach requires understanding how CI-dimension behaves under iteration of the endomorphism.

Specifically, determining whether the CI-dimension finiteness of R_φ propagates to R_{φn} for n ≥ 1 would align module-theoretic finiteness conditions with endomorphism-based invariants and clarify the relationship between different regularity and complete intersection tests.

References

As far as the author is aware, these results are separated by two open problems. The second is whether finiteness of \cid_R(R_\phi) < \infty implies \cid_R(R_{\phin}) < \infty.

A Ghost Lemma for Commutative Ring Homomorphisms via André-Quillen Homology (2507.13988 - McCormick, 18 Jul 2025) in Remark rem:majadas, Section 7 (Applications to Singularities)