11,439 reputation
43595
bio website ncatlab.org/nlab/show/…
location Adelaide, Australia
age 31
visits member for 5 years, 6 months
seen 7 hours ago

Pure mathematician interested in category theory and foundations.


2d
comment Differential Topology over $\mathbb{Q}$
@SimonHenry - really? The disjoint union of uncountably-many copies of $\mathbb{R}$ is paracompact is it not? Or are you assuming second countability in your definition of 'ordinary manifold'?
May
21
comment Can a cylinder be regarded as a Riemannian manifold?
You could consider it as a CAT(n) space, perhaps...
May
21
comment Alternating Reciprocal of Squares
The sum expression was wrong, so I corrected it. The alternating series converges, since the series converges absolutely. Not sure if this question will be well received.
May
21
revised Alternating Reciprocal of Squares
Corrected sum expression
May
21
comment try to calculate the probability
This question is off-topic. MO is (to a first approximation) for questions for professional researchers in mathematics.
May
21
comment A model category of abelian categories?
@TheoJohnson-Freyd The paper is at arxiv.org/abs/1402.7108
May
20
comment What's so great about blackboards?
The thing that any slide presentation, with current technology lacks, is real estate. Unless one is stuck with a tiny board the size of a projector screen, you have so much more to play with (six boards! eight boards!! Imagine having that many simultaneous projected slides)
May
19
comment Suggest a reading list to start TQFT
I suggest this question might be suited to math.stackexchange. More detail about your background might help, since 'a graduate degree in physics' contains different levels of maths depending where you are.
May
18
comment Intrinsic definition of arc length
@Joonas by 'trace' do you mean the image of a defining function? Assuming a finite set of self-intersection points should sort that out (or perhaps measure zero!)
May
18
comment I have to show any non-invertible matrix is a reducible matrix
Why do you have to show it?
May
18
comment Intrinsic definition of arc length
@Cusp probably not. Such an approximation only requires a bunch of points on the curve, and one can define the error of the approximation via the sum of the maximum and the minimum of the length of the line segments in the approximation. Presumably for rectifiable curves as this 'error' approaches zero the usual distance (L^1 metric, say) approaches zero.
May
18
answered Old books still used
May
18
comment Mathematical research papers in general science journals
@Gerry well I never. +1 for you! It does sit under the heading 'Physical sciences' - a slight lie - but with subheading 'Mathematics'. I note with interest that a mere three more mathematics papers have been published since I wrote this answer. Not exactly a flood...
May
16
comment Vandermond Invers using Lagrange
This is off-topic. Do you want a Matlab-specific forum instead? Or otherwise there are other stackexchange sites that may help.
May
15
comment explicit integrals over a Lie group
And for some other functions mathoverflow.net/questions/36025/…
May
15
comment explicit integrals over a Lie group
Examples involving f=1: mathoverflow.net/questions/84848/… mathoverflow.net/questions/203836/volume-of-the-unitary-group
May
15
comment How to learn QFT from mathematical perspective?
Note that we don't actually understand QFT mathematically! (In general). There are bits and pieces we know, but it's like knowing calculus in the 18th century: hacks, tricks and a few good examples, but no overarching rigorous mathematical framework.
May
14
revised Henstock, Differentiation under the integral sign
added 434 characters in body; edited tags
May
12
revised About the trace class operators and their motivation
added 57 characters in body
May
12
comment A model category of abelian categories?
@TheoJohnson-Freyd well, let me finish editing it first :-) It will most definitely be on the arXiv before the publisher gets their hands on it.