Eight papers have been published by Algebraic & Geometric Topology.
This completes publication of volume 7 (2007) of AGT. Volume 8 will
commence publication in January 2008.

(1) Algebraic & Geometric Topology 7 (2007) 1987-2006
The center of some braid groups and the Farrell cohomology of certain
pure mapping class groups
by Yu Qing Chen, Henry H Glover and Craig A Jensen
URL: http://www.msp.warwick.ac.uk/agt/2007/07/p076.xhtml
DOI: 10.2140/agt.2007.7.1987

(2) Algebraic & Geometric Topology 7 (2007) 2007-2020
The homotopy Lie algebra of the complements of subspace arrangements
with geometric lattices
by Gery Debongnie
URL: http://www.msp.warwick.ac.uk/agt/2007/07/p077.xhtml
DOI: 10.2140/agt.2007.7.2007

I have been looking at the Jacobi Method for finding eigenvalues of a
symmetric matrix. Using google, I found references that said it
converges with quadratic order when the eigenvalues are distinct.

What is known about the speed of convergence when the eigenvalues are
not necessarily distinct?

Thanks, Stephen

Where can I learn what is known about the diffeomorphism group of real
n-space?

From what I can tell, this info seems to be scattered about the
journals (and presumably lecture notes). Not being an expert in this
area, I seek a single source such as a review (precis, summary, etc.)
to get me into the relevant literature.

I need the information for some research I am doing into nonlinear
Ehresmann connections.

Hello,

Let X be a set and R be an ordering relation on X. Then C(X,R) denotes
the set of linear ordering relations containing R. It is well-known
that C(X,R) is non-empty (Szpilrajn's theorem) and that the
intersection of C(X,R) equals R.

The order dimension of (X, R) is defined to be

min { card(K) : K \subseteq C(X,R) and \bigcap K = R }.

Is there a connection / relationship between the order dimension of a
poset and the topological covering dimension of X endowed with the
interval topology?

Thanks, Dominic

Hi there,

I have the following question. I wonder if you could help me to
solve...I believe it is true...

Question: For odd r, to prove that
H_r(x)-1 or H_r(x)+1 is irreducible over rationals,

where H_0(x)=1, H_1(x)=x, H_(r+1)(x)=xH_r(x)-(d-1)H_(r-1)(x)

and d>=3 is a positive integer.

Thanks a lot,
Guille

Hi,

Can you find strategies for minimizing the number of moves made in
this number/slider hybrid puzzle?

http://www.facebook.com/apps/application.php?id=20690165651

Amir

Also available as http://math.ucr.edu/home/baez/week260.html

December 24, 2007
This Week's Finds in Mathematical Physics (Week 260)
John Baez

Since it's Christmas Eve, I thought I'd list some free books you
can download. I'm a big fan of giving the world presents... and
I'm not the only one.

But first, this week's nebulae! Here's one called the Retina:

1) Retina Nebula, Hubble Heritage Project,
http://heritage.stsci.edu/2002/14/

This is actually a tube of ionized gas about a quarter of a light-year
across and one light-year long. It's a planetary nebula produced
by a dying star. If you zoom in and look closely, you can see this
star lurking in the middle, now a mere white dwarf.

The blue light is the most energetic, so it's really hot where you see
blue. This blue light comes from singly ionized helium - helium where
one electron has been knocked off. The green light is a bit less
energetic: that's from doubly ionized oxygen. The red light comes from
even cooler regions: that's from singly ionized nitrogen.

hi,
i was wondering as to what exactly is the relationship between
categorical limits and the usual notion of limits in topological
spaces. more specifically, two naive questions :
can one impose topological structure on a category so that notion of
limits coincide?
can one derive a category from the category of open sets in a
topological space in which somehow points correspond to limits?
thanks,
harsha

We're hiring:

http://www.jobs.ac.uk/jobs/TN992/Lectureship_Senior_Lectureship_Readership/

There are three posts available, one in analysis and the other two in
more or less any part of pure mathematics. All are tenured.

For those unfamiliar with UK terminology, here's a brief explanation of
the job titles. Someone with tenure is called a lecturer, senior
lecturer, reader or professor. A lectureship is the most junior post (but
not like an American lectureship). Senior lecturer and reader are
intermediate posts; SL is more oriented towards teaching, and reader
towards research. There are rather few professors (maybe 20%% of the
faculty), and it's perfectly normal to end one's career without ever
becoming one.

Details of how to apply can be found by following the link.

Tom

On Dec 13, 3:49 pm, ulfarsson gmail.com> wrote: