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 39777

Commutative rings, modules, ideals, homological algebra, computational aspects, invariant theory, connections to algebraic geometry and combinatorics.

2 votes

Flat algebra over polynomial ring

Let's call $A = k[x_1, \dots, x_r; u_1, \dots, u_s]$. If $u_1, \dots, u_s \in R^\times$, then $i: A \to R$ factors through the localization $A_u$ with respect to $u = u_1 \cdots u_s$. Localization is …
Eric Canton's user avatar
5 votes
Accepted

Geometric interpretation of algebraic tangent cone

You may wish to read the discussion on pages 106-108 of Eisenbud/Harris "The Geometry of Schemes", where they explicitly compute the tangent cone of $(y^2-x^3)$ as a degeneration of the tangent cones …
Eric Canton's user avatar
2 votes
Accepted

characterisation of regular morphisms

Yes, these are equivalent. See Srikanth Iyengar's write-up on Andr\'e-Quillen homology. Specifically, Theorem 9.5 (together with Proposition 5.9) proves exactly what you want, and a little more. The t …
Eric Canton's user avatar
5 votes
2 answers
767 views

Does the degree of a finite dominant morphism bound the induced degree on subschemes?

Suppose $f: \widetilde{X} \to X$ is a finite dominant morphism between connected, normal, Noetherian schemes, and that this morphism induces a dominant morphism $f_W: \widetilde{W} \to W$ between conn …