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Local cohomology and image of $1$ under the canonical map from Ext to local cohomology

Let $R$ be a commutative Noetherian local ring, and $S$ be an $R$-algebra. Let $x_1,\dots,x_t$ be elements, in the maximal ideal of $R$, which is a regular sequence on both $R$ and $S$, and let $I$ be ...
uno's user avatar
  • 412
1 vote
1 answer
106 views

On $\text{depth}_S\left(\dfrac {S}{JS+xS}\right)$, when $\text{depth}_R(R/J)=0$, and $R\to S$ is a certain flat map of local rings

Let $(R, \mathfrak m) \xrightarrow{\phi} (S,\mathfrak n) $ be a flat homomorphism of local rings such that $\mathfrak n=\mathfrak m S +xS$ for some $x\in \mathfrak n \setminus \mathfrak n^2$. Let $J$ ...
feder's user avatar
  • 73
7 votes
2 answers
734 views

invariants that can be measured by Local Cohomology

What invariants can be measured by Local Cohomology (and what application it has)? As an example of what I mean: Local Cohomology can measure invariants like depth and dim. So in some cases Local ...
user 1's user avatar
  • 1,355
5 votes
0 answers
94 views

How far finiteness dimension can be from edges? Example for $f_m(S/I)\ge depth S/I+2$

Let $ (R,m) $ be a commutative unital noetherian local ring (with $m$ as its maximal ideal), $ I $ an ideal of $ R $, and $ M $ a finite $R$-module with $\dim M\gt 0$. $f_I(M) = \inf\ \{i : H_I^i(M)\ ...
user 1's user avatar
  • 1,355
2 votes
1 answer
288 views

finiteness dimension

$R$ is a local Noetherian ring. $f_I(M)$, the finiteness dimension of a module $M$ relative to $I$, is defined in ...
user 1's user avatar
  • 1,355
1 vote
1 answer
211 views

Is there a prime of height $i$ in support of $H^i_I(R)$?

$I$ is an ideal of a local Noetherian ring $R$ and $i>0$ . Clearly the height of primes in support of $H^i_I(R)$ is at least $i$ The question is if it contains a prime of height $i$, specially ...
QED's user avatar
  • 189