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 6153

Complex, contact, Riemannian, pseudo-Riemannian and Finsler geometry, relativity, gauge theory, global analysis.

3 votes

Genus of complex projective space

Talking about the arithmetic genus (http://en.wikipedia.org/wiki/Arithmetic_genus), it's the alternating sum of Hodge numbers all of which are 0. So, in short, yes.
Charles Matthews's user avatar
4 votes

Compactification of a manifold

What do you want to do with an open annulus in the plane? Already open subsets of the plane may need infinitely many points added to compactify them in a sensible way.
Charles Matthews's user avatar
3 votes
Accepted

Is the object we get when we quotient $U(N)$ by $U(N-k)$ familar?

Putting a name to the space, it's a complex Stiefel manifold. See http://en.wikipedia.org/wiki/Stiefel_manifold. (But I wasn't the first.)
Charles Matthews's user avatar
2 votes

What is the best way explain to undergraduates that all 1-dimensional manifolds are orientable?

I'm struck by the idea that one ought to prove first that there is a Morse function, and work out orientability and other things as corollaries.
Charles Matthews's user avatar
3 votes

Can a smooth, immersed loop in R^2 become not nullhomotopic by removing a point?

For a different way of looking at the same issue see http://en.wikipedia.org/wiki/Pochhammer_contour . The contour is set up to have winding number 0 around any point.
Charles Matthews's user avatar
4 votes

What is a square root of a line bundle?

Try http://en.wikipedia.org/wiki/Theta_characteristic . Since the product of line bundles is tensor product, "square root" is in the same sense. So your comment is correct.
Charles Matthews's user avatar
10 votes
1 answer
2k views

What is the current state of the mathematics of Higgs fields?

Topical. I know there are good mathematical theories in which "Higgs" is used, in a geometrical sense. Would someone care to explain? To clarify, I'd like to know about Higgs bundles on Riemann surfa …
Charles Matthews's user avatar
7 votes

Why study Lie algebras?

As has been said, Lie groups are our best theory encoding continuous symmetry. Lie algebra theory, which is the infinitesimal counterpart, is a theory good enough that numerous problems can be solved …
Charles Matthews's user avatar