4,201 reputation
21747
bio website bruno.stonek.com
location Montevideo, Uruguay
age 25
visits member for 3 years, 11 months
seen 6 hours ago

Math student at Université Paris 13.


Mar
14
comment If a morphism of pushouts of complexes (with one arrow monic) is composed of quasi-isos, then the induced arrow is one also
@ZhenLin: Thanks. I'll roll up my sleeves and diagram-chase in that particular case then, I guess. I'm intrigued about your comment about homotopy colimits though, if you would like to expand on it (maybe as an answer?) it would be great :)
Mar
14
comment If a morphism of pushouts of complexes (with one arrow monic) is composed of quasi-isos, then the induced arrow is one also
@Zhen: What if one of the arrows is a monomorphism (in the case of the pushout)?
Mar
14
asked If a morphism of pushouts of complexes (with one arrow monic) is composed of quasi-isos, then the induced arrow is one also
Mar
14
comment Mayer-Vietoris Type Sequence For Pushouts
One little comment. A nice reference for homotopy pushouts/pullbacks is Arkowitz's Introduction to homotopy theory. In particular, the second sentence of your second paragraph is proposition 6.2.6.
Mar
12
reviewed Approve suggested edit on Probability of at least one male and one female sharing the same birthday
Mar
10
comment Simply connected reduced suspension on path connected X
@JuanS: I haven't read the posts in detail, but in the first one the counterexample he produces involved the Hawaiian earring which does not satisfy the hypotheses of Freudenthal's suspension theorem.
Mar
6
awarded  Nice Answer
Feb
24
reviewed Reject suggested edit on What makes a limit 'go away'?
Feb
24
reviewed Reject suggested edit on truth tables and validity of arguments
Feb
23
comment The fundamental group of a topological group is abelian
Hey, cute abstract nonsense proof! Thanks for posting it! (+1)
Feb
21
accepted Is an integer a sum of two rational squares iff it is a sum of two integer squares?
Feb
18
reviewed Reject suggested edit on Differentiable function on bad sets.
Feb
10
reviewed Approve suggested edit on Evaluating $\int\frac{3x+1}{2x^2-2x+3}dx$
Feb
8
reviewed Approve suggested edit on At least one prime between N and N-(sqrtN)
Feb
7
comment The groups $[\Sigma^nX,Y]$ versus the homotopy groups
@nik: I understand what you're saying now. But the questions are the end are to be taken to mean: "in these circumstances, does the knowledge of these groups for all $X$ give us information?" (the questions you linked being taking $X=S^0$)
Feb
7
comment The groups $[\Sigma^nX,Y]$ versus the homotopy groups
@nik: as interesting as those questions may be, I don't see any reference to the groups I allude to in this one.
Feb
7
comment The groups $[\Sigma^nX,Y]$ versus the homotopy groups
@ZhenLin: yes, but of a different space! In any case, thanks, that's a nice observation.
Feb
7
asked The groups $[\Sigma^nX,Y]$ versus the homotopy groups
Jan
31
asked Homology with local coefficients in a $\mathbb{Z}[\pi_1(X)]$-module
Jan
27
comment Does there exist a surface homemomorphic to a torus with positive Gaussian curvature?
@Felipe: any compact surface in $\mathbb{R}^3$ has a point with positive curvature. Indeed, it is bounded, thus it lies inside of a big enough sphere. Now reduce the sphere's radio until it first touches the surface in a point. That point of the surface must therefore have positive curvature. (You should fill in the details for this argument).