3,490 reputation
1231
bio website mathstat.dal.ca/…
location Stockholm, Sweden
age 31
visits member for 4 years, 10 months
seen 20 hours ago

math.LO/math.CT, currently postdoc at Stockholm University. Previously Institute for Advanced Study, Princeton, lately of Dalhousie University, Nova Scotia, and Carnegie Mellon University, Pittsburgh.


Oct
12
comment Concise definition of subobjects
I think the well-poweredness is beside the point: the main thing is that the groupoid core of the the category of subobjects is essentially discrete, and so we are quotienting by unique isomorphisms, which is generally well-behaved.
Oct
2
comment What is the Shortest Axiom of Classical Conditional-Negation Propositional Calculus?
In infix notation, perhaps slightly more readable than prefix: [(((p→q)→(¬r→¬s))→r)→t] → [(t→p)→(s→p)].
Sep
29
comment What is the most useful non-existing object of your field?
This function exists; it just isn’t computable. A program computing this function could arguably be an answer.
Sep
29
comment What is the most useful non-existing object of your field?
One can also argue that this one does exist, perfectly happily: it’s just a class that isn’t a set.
Sep
23
revised Discrete Morse theory and existence of minimal complex
retagged (now that DMT tag exists)
Sep
16
revised discrete-morse-theory wiki description
initiated wiki entry for new tag
Sep
16
revised discrete-morse-theory wiki excerpt
initiated wiki entry for new tag
Sep
16
revised Morse matching with 0-cells and (n-1)-cells
retagged (now that this tag exists)
Sep
16
revised Discrete Morse theory and chess
retagged (now that tag exists)
Sep
16
suggested suggested edit on discrete-morse-theory tag wiki
Sep
16
wiki created discrete-morse-theory description
Sep
16
wiki created discrete-morse-theory excerpt
Sep
16
suggested suggested edit on discrete-morse-theory tag wiki excerpt
Sep
16
revised Using Discrete Morse Theory to represent hom classes
edited tags
Sep
15
comment Results true in a dimension and false for higher dimensions
To elaborate on this: in dimensions ≥3 there are finite paradoxical decompositions of the unit ball; in dimensions 1 and 2, paradoxical decompositions must be countably infinite; and in dimension 0, there are none.
Sep
15
revised Besides the tracioid are there other surfaces of revolution that have a constant negative curvature?
made answer a little more informative without needing to click through
Sep
7
revised Pseudonyms of famous mathematicians
updated link, as per comments (while this thread is already recently bumped)
Jul
29
comment Do direct limits (filtered colimits) commute with pullbacks, in C*-algebras?
Both at math.se and here, the title was rather unclear, which I think is why there’s been some misunderstanding and negative reactions in comments (including thinking that the question was more trivial than it is). I’ve edited the title to give the actual question a bit more clearly; hopefully I’ve understood OP’s intentions correctly.
Jul
29
revised Do direct limits (filtered colimits) commute with pullbacks, in C*-algebras?
Clarified title to give question more specifically
Jul
25
comment Why do Lie algebras pop up, from a categorical point of view?
“The category of Lie algebras is equivalent to a certain category of cocommutative Hopf algebras” — do you know a good reference that works this out or states it more precisely? Or at least some specific term which readers can google for more details?