bio  website  maths.ed.ac.uk/~tl 

location  
age  
visits  member for  5 years, 10 months 
seen  4 hours ago  
stats  profile views  7,510 
14h

comment 
Classifying spaces for enriched categories
Thanks for the clarification. 
2d

comment 
Classifying spaces for enriched categories
Vidit, I'm not sure what you mean. The 0simplices of $\Delta C$ are the objects of $C$, sure. But if $x_0$ and $x_1$ are objects of $C$, what is the set of 1simplices in $\Delta C$ from $x_0$ to $x_1$? And in your item 1, is $f_{ij}$ just any object of $V$? Finally, is this really answered in Bullejos and Cegarra's paper? I could only see the special case $V = \mathbf{Cat}$, i.e. classifying spaces of 2categories (as their title suggests). 
Aug
20 
comment 
Categorical product of graphs and chromatic number
For all we currently know, there might be an inequality the other way round too (at least, for a finite family of finite graphs). That's exactly Hedetniemi's conjecture. Here's a categorical account: golem.ph.utexas.edu/category/2014/12/… 
Jun
13 
answered  Reference for an unbiased definition of a symmetric monoidal category 
Jun
12 
comment 
A good place where to learn about derived functors
Fixed. I've moved jobs since writing this answer, and the link was to my old website. 
Jun
12 
revised 
A good place where to learn about derived functors
updated link 
Jun
6 
comment 
For a ring $k$ and a set $X$, what are the $k$algebra homomorphisms $k^X \to k$?
Thanks, Eric. So in particular, whether there exist nontrivial maps $k^X \to k$ depends only on $X$ and the cardinality of $k$, at least when $k$ is a field. 
Jun
6 
accepted  For a ring $k$ and a set $X$, what are the $k$algebra homomorphisms $k^X \to k$? 
Jun
4 
comment 
For a ring $k$ and a set $X$, what are the $k$algebra homomorphisms $k^X \to k$?
@ArturoMagidin: Thanks for the edit, Latexifying the title. I seem to recall a meta discussion a while ago in which various people said Latex in titles should be kept to a minimum. It was a matter of speeding up rendering on slow devices or slow network connections. That's why I wrote the title in plain text. But I'm not so bothered about it that I'm going to change it back. 
Jun
4 
revised 
For a ring $k$ and a set $X$, what are the $k$algebra homomorphisms $k^X \to k$?
improved wording 
Jun
4 
comment 
For a ring $k$ and a set $X$, what are the $k$algebra homomorphisms $k^X \to k$?
@TomGoodwillie: Thanks! Your argument implies that if $X \leq k$ then there are no nontrivial homomorphisms $k^X \to k$, doesn't it? 
Jun
4 
comment 
For a ring $k$ and a set $X$, what are the $k$algebra homomorphisms $k^X \to k$?
@YCor: I don't have a particular interest in large cardinals, thanks, but neither do I particularly want to rule out sets of large cardinality. 
Jun
4 
asked  For a ring $k$ and a set $X$, what are the $k$algebra homomorphisms $k^X \to k$? 
May
26 
awarded  Good Question 
Mar
3 
awarded  Famous Question 
Mar
2 
comment 
On the coherence theorem for bicategories
If you want a quick overview of the situation, you could try the slides here, especially pages 8 and 14: maths.ed.ac.uk/~tl/toronto 
Jan
22 
awarded  Popular Question 
Jan
18 
awarded  Good Answer 
Jan
17 
awarded  Enlightened 
Jan
16 
awarded  Nice Answer 