466 reputation
36
bio website pages.bangor.ac.uk/~mas013
location Ynys Mon, Cymru (i.e. Anglesey, Wales, UK)
age 67
visits member for 3 years, 9 months
seen Dec 16 at 16:59

I was professor of mathematics at the University of Wales Bangor. The university shut the mathematics department. For more info. see my nLab page.


Dec
9
awarded  Caucus
Mar
8
comment How can a functor which preserves products not be natural?
To me it is not clear what exactly you mean by saying that the isomorphism between $XZ$ and $X\times Y$ is not natural. You should check up on the precise meaning of natural in this context.
Mar
6
comment Fundamental group of row of spheres
... but are your 5 generators independent of each other? Try to find a homotopy equivalence from your space to the bouquet of n-circles. Look up the van Kampen theorem as well. Finally, for fun what about the infinite (or the doubly infinite rows of circles????
Mar
2
comment Telescopic groups
@Ryan: I think the point is that in the subgroup lattice of a group there may be many different `copies' of a group, so you have to think of them as being different subgroups since they are! There are also logical problems in thinking of a group as an isomorphism calss of groups, as then what does an automorphism of that group give. This, of course, can be avoided but that can get very confusing. You may or may not like a categorical viewpoint but taking a more categorical view does get around this and makes the overall structure more transparent.
Feb
27
comment Topics in combinatorial Group Theory
Loday's paper is a good one to get those aspects of pictures and has the references to Igusa.
Feb
27
comment Topics in combinatorial Group Theory
Igusa is credited with them as well and may have the edge on Steve Pride. My main point is that that material is a very nice intro to some of the outward looking links from Comb. Group Theory. It is fun, and easy to present as it does not require that much background.
Feb
27
answered Topics in combinatorial Group Theory
Feb
10
comment Referencing something that isn't a lemma, proposition etc…
I feel that the second and third are more or less equivalent, and which you use is then a question of the actual fact that is being referred to and how it is presented in ref. [1]. The point is to see in any particular case which form works best for you (and test it on others). Don't worry about unwritten rules, seek clarity of express instead. (Unwritten rules may be right or wrong, and as they are unwritten how can one tell. ;-))
Feb
10
comment Why do people not use “partially directed” graphs?
... but then it is convenient to draw that graph as one with some edges having arrows on them and others not so! The point is thus more that these graphs are very common, but can be reduced to examples of directed graphs.
Dec
27
comment Mathematics and slavery
The question is at present a bit imprecise. The system of slavery used by different civilisations was very varied. The form of what we call slavery in ancient Greece is therefore important in its detail. Athens also had a large network of tribute providers which led to the rise of a class with leisure time. There are other factors that may be just as important however.
May
28
awarded  Yearling
Oct
3
answered What should a math graduate know?
Jun
27
awarded  Enlightened
Jun
27
awarded  Nice Answer
Mar
24
awarded  Yearling
Jan
30
answered A very vague question about the cartesian product in mathematics.
Jan
6
answered Notes on dga's with a look towards Rational Homotopy Theory?
Dec
13
comment Is category theory useful in higher level Analysis?
You might repost this question to MO as it may attract more replies there. Also there has been some mention of categories of Banach spaces, Banach bundles etc on discussions on the nForum and entries in the nLab, so have a look over there as well.
Sep
23
answered What is a“canonical morphism” in a category?
Aug
24
awarded  Commentator