Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 460

For questions on modules over rings.

9 votes
Accepted

Are there two non-isomorphic modules such that all the Hom-sets are isomorphic?

K. Bongartz, "A generalization of a theorem of Auslander": Let R be a commutative ring and A an abelian R-linear category such that each morphism set in A has finite length as an R-module. Let …
Graham Leuschke's user avatar
10 votes

Classification of pairs of commuting endomorphisms

The classification of $K[X,Y]$-modules of finite length is of wild type, meaning that a classification of these modules would contain within it a classification of all finite-dimensional $\Lambda$-modules … In fact, even the classification of those $K[X,Y]$-modules annihilated by $(X^2, XY^2,Y^3)$ is a wild problem, as shown by Drozd. …
Graham Leuschke's user avatar
4 votes
Accepted

Homological dimensions of module

See Fossum, Foxby, Griffith, and Reiten, "Minimal injective resolutions with applications to dualizing modules and Gorenstein modules" (Theorem 1.1) and also Roberts, "Two applications of dualizing complexes …
Graham Leuschke's user avatar
2 votes

when there is an injection $0 \to R \to K_R$?

As soon as the dimension of $R$ is at least $1$ and $R$ is locally Gorenstein at the associated primes, then $K$ is isomorphic to an ideal of pure height $1$. In particular $K$ (as an ideal) contains …
Graham Leuschke's user avatar
8 votes
Accepted

Extension problem

$\mathrm{Ext} = \mathrm{Ext}^1$ does not classify the middle terms up to isomorphism. It classifies the short exact sequences up to equivalence, where the equivalence relation is generated by commuta …
Graham Leuschke's user avatar