## August 24, 2005

### CFT, Gerbes and K-Theory in Oberwolfach, VII

#### Posted by Urs Schreiber

You’ll have noticed that I failed to report on the talks of the last two days in Oberwolfach, either because I was too tired, or too occupied or both. Here are some symposium-postprocessing notes.

Update: Peter Woit has followed the Oberwolfach discussion here and has written a related entry.

While searching for literature on what I now know is called ‘differential’ or ‘smooth’ K-theory I came across the report of another recent Oberwolfach workshop which is very closely related to the things I mentioned here recently:

P. Teichner & St. Stolz (Eds.)
Geometric Topology and Connections with Quantum Field Theory
OW Report No. 27/2005

This report is valuable for the references it assembles.

In the above fashion, every participant of an Oberwolfach workshop is supposed to provide a summary of his talk for the OW-Reports. A draft for my summary is the one below:

Posted at 1:32 PM UTC | Permalink | Followups (8)

## August 22, 2005

### Lecture Notes on Higher Gauge Theory

#### Posted by Urs Schreiber

John Baez is giving a lecture on Higher Gauge Theory, Homotopy Theory and $n$-Categories in Calgary. The lecture notes are available online.

## August 20, 2005

### CFT, Gerbes and K-Theory in Oberwolfach, VI

#### Posted by Urs Schreiber

With kind permission, here are more details on Brano Jurčo’s talk:

Branislav Jurčo
On the Classification of Nonabelian Bundle Gerbes with Connections
(in preparation)

Update 5th October 2005: The corresponding preprint has now appeared as math.DG/0510078.

Posted at 1:43 PM UTC | Permalink | Followups (9)

## August 17, 2005

### CFT, Gerbes and K-Theory in Oberwolfach, V

#### Posted by Urs Schreiber

Wednesday in Oberwolfach. The obstructions for the sun to shine finally lifted and we had something that even people from Australia would recognize as a summer day.

The workshop now has a webpage on which links to slides and other background information will eventually appear:

Workshop Gerbes, twisted K-theory and conformal field theory

Posted at 8:18 PM UTC | Permalink | Followups (6)

## August 16, 2005

### CFT, Gerbes and K-Theory in Oberwolfach, IV

#### Posted by Urs Schreiber

Posted at 8:59 PM UTC | Permalink | Followups (5)

## August 15, 2005

### CFT, Gerbes and K-Theory in Oberwolfach, III

#### Posted by Urs Schreiber

This evening in Oberwolfach: Talks on open strings in WZW models and lots of private discussion.

### CFT, Gerbes and K-Theory in Oberwolfach, II

#### Posted by Urs Schreiber

Oberwolfach is the mixture of a Zen monastery with a mathematical bioreactor. Nice experience.

Posted at 12:40 PM UTC | Permalink | Followups (2)

## August 12, 2005

### K-theory for dummies, I

#### Posted by Urs Schreiber

I feel like talking about K-theory, K-homology, and the like. Here I start leisurely with a bird’s eye overview of some central ideas.

Posted at 7:14 PM UTC | Permalink | Followups (34)

### CFT, Gerbes and K-Theory in Oberwolfach, I

#### Posted by Urs Schreiber

Next week I’ll be attending a mini-workshop at the MFO in Oberwolfach titled

organized by Branislav Jurčo, Jouko Mickelsson and Christoph Schweigert.

If possible, I’ll try to report on this and that here at the Coffee Table.

Posted at 10:15 AM UTC | Permalink | Followups (14)

## August 2, 2005

### Background independence

#### Posted by Robert H.

Last week, Lee Smolin has put a paper on the arxive which on nearly fifty pages does not contain any formulas. Still, he claims it reveals the reason for the failures of string-theory: Background dependence. Lubos has already discussed it in his reference frame. Even so my boss has advised me that this is a waste of time I have written up some comments on that paper. I would love to read you comments, suggestions and criticism. I don’t think this is a waste of time (as long at it does not take too much of my time) as I assume (given for example the comments over at the Cosmic Variance) Smolin’s arguments would appeal especially to outsiders of the field. We should prevent too many people from getting the idea that “string theory is obviously wrong as it ignores the basic notion of background independence”. So I collected some thoughts that might help you arguing the next time you are envolved in this debate.
Posted at 3:20 PM UTC | Permalink | Followups (57)