What is K-theory and what is it good for?

Paul F. Baum (Penn State University, State College, USA)

[rosieshen]

11:57 lecture starts
12:56 basic definitions
28:43 history of K-theory
44:53 tangent vector field on spheres
58:26 K-theory for C^*-algebras

[jackozeehakkjuz]

How does this have so few views?! this is wonderful. Excellent exposition, crystal clear and very inspiring. Thank you very much for sharing!

[timpani]

What a great lecture! Would recommend as a good starting point for anyone wishing to study K-theory.

[alexandershapiro]

This is the best video for an introduction of k-theory that I found, together with math-life-balance was a "juicy" math indeed.

[imrematajz]

This might be an absolute no-brainer for someone in the know: K-theory = Kategory theory given the implicit description referring to functoriality. It would have put me out of my misery early on if this had been made clear from the word get go. The meat can be found starting from 1:04:22 examples. Relation to P-adic and Adelic groups is a revelation!

[qwertyqwert]

It is nice if this view is correct. I do not have the expertise to verify, if this is all true.. I truly hope this all correct. The example given at at 27. minute did not work for x1=2, x2=3, x3=2 . This means if A=[(1+2)/2, (2+1j*3)/2;(2-1j*3)/2, (1-2)/2]; or A=[1, 0, 0;0, (1+2)/2, (2+1j*3)/2;0, (2-1j*3)/2, (1-2)/2] A is not equal to A*A?

[stevelam]

You lost me at "Suppose we have an abelian semigroup".

[ciaopeople]

K-theory, huh, yeah
What is it good for?
Absolutely nothing, uhh

[clickaccept]

The general principle of conemporary mathematics, is attach the word "theory" to soemthing. Then you have a career. apparently.