Dear Colleagues, 
I have this month to move my web site
http://pages.bangor.ac.uk/~mas010
 from Bangor University; the new web site (but still under construction!) is 
www.groupoids.org.uk
So if you wish to keep links they   should be changed as illustrated below
html or htm files 
http://pages.bangor.ac.uk/~mas010/pstacks.htm/.html
to
http://groupoids.org.uk/pstacks.html
pdf files 
http://pages.bangor.ac.uk/~mas010/pdffiles/groupoidsurvey.pdf 
to
http://groupoids.org.uk/pdffiles/groupoidsurvey.pdf
images (jpg, gif,..)
http://pages.bangor.ac.uk/~mas010/composition2.jpg
to 
http://groupoids.org.uk/images/composition2.jpg
One consequence of this is that the many links from mathoverflow and mathstackexchange will not work, and should be changed manually as above. If anyone wants to help on their own initiative in this 
I'd be grateful indeed (and I hope also  the readers)! I have checked at 
http://mathoverflow.net/questions/3656/cubical-vs-simplicial-singular-homology/83666#83666
that these changes work. 
 My son Marcus has done  the new web design and I am gradually getting used to it, but there is still work to be done on it. Please let me know of problems. 
The old site has had over 700 page views in the last 30 days, with quite a lot of pdf downloads.  I hope the new site will in the end be more useful. The old site did need revision to modern standards, and the new one and its separate hosting has also the advantage  of the capability of outlasting me. 
Regards
Ronnie Brown