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 40804

Questions about the branch of algebra that deals with groups.

5 votes
Accepted

Injectivity of the cohomology map induced by some projection map

Ok, I will follow Fernando's advice and post an answer. I learned the computation below from the beginning of Pin(2)-equivariant Seiberg--Witten Floer homology and the triangulation conjecture. The gr …
mme's user avatar
  • 9,580
54 votes

Is SO(4) a subgroup of SU(3)?

No. There is probably a straightforward representation-theoretic argument, but I am too ignorant of the subject to give one, so here is a topological argument. If $H \subset G$ are Lie groups with $H$ …
mme's user avatar
  • 9,580
9 votes

Classifying space of semidirect product of groups

I am adding my comment as an answer. Every extension of groups $1 \to H \to G \to K \to 1$ corresponds to a fibration $$BH \to BG \to BK,$$ or a little more precisely at the space level $$EG/H \to (E …
mme's user avatar
  • 9,580
2 votes
Accepted

Monoid of continuous self-maps of (real) surfaces

Here's some sort of geometric description of maps of degree 0. I don't know how realistically you can find a generators-and-relations description of the semigroup of such maps. It is a theorem due to …
mme's user avatar
  • 9,580