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LOCAL COHOMOLOGY UNDER SMALL PERTURBATIONS
- Part of
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- Journal:
- Nagoya Mathematical Journal , First View
- Published online by Cambridge University Press:
- 20 January 2025, pp. 1-18
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- Article
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Let
$(R,\mathfrak {m})$ be a Noetherian local ring and I an ideal of R. We study how local cohomology modules with support in 
$\mathfrak {m}$ change for small perturbations J of I, that is, for ideals J such that 
$I\equiv J\bmod \mathfrak {m}^N$ for large N, under the hypothesis that 
$R/I$ and 
$R/J$ share the same Hilbert function. As one of our main results, we show that if 
$R/I$ is generalized Cohen–Macaulay, then the local cohomology modules of 
$R/J$ are isomorphic to the corresponding local cohomology modules of 
$R/I$, except possibly the top one. In particular, this answers a question raised by Quy and V. D. Trung. Our approach also allows us to prove that if 
$R/I$ is Buchsbaum, then so is 
$R/J$. Finally, under some additional assumptions, we show that if 
$R/I$ satisfies Serre’s property 
$(S_n)$, then so does 
$R/J$.
