4,136 reputation
21647
bio website bruno.stonek.com
location Montevideo, Uruguay
age 25
visits member for 3 years, 10 months
seen 3 hours ago

Math student in Université Paris 13.


Dec
10
accepted Every 4-dimensional isotropic quadratic space of determinant 1 is hyperbolic
Dec
10
accepted In a complete perfect metric space, transitive distance-preserving maps are minimal
Dec
1
awarded  Popular Question
Nov
28
comment tensor product and direct product of algebra presentations
I think you meant $xy-yx$ on your displayed equation.
Nov
26
asked Is an integer a sum of two rational squares iff it is a sum of two integer squares?
Nov
26
comment Every 4-dimensional isotropic quadratic space of determinant 1 is hyperbolic
The thing is, the same proof that any 2-dimensional isotropic quadratic space is hyperbolic proves that any isotropic quadratic space contains an hyperbolic plane! That's the essential piece I was missing out on.
Nov
26
answered Every 4-dimensional isotropic quadratic space of determinant 1 is hyperbolic
Nov
21
accepted How to prove that two dilations of $\mathbb R^n$ are conjugate?
Nov
21
asked Every 4-dimensional isotropic quadratic space of determinant 1 is hyperbolic
Nov
14
comment In a complete perfect metric space, transitive distance-preserving maps are minimal
Gracias Gordo por la ayuda.
Nov
14
answered In a complete perfect metric space, transitive distance-preserving maps are minimal
Nov
13
asked In a complete perfect metric space, transitive distance-preserving maps are minimal
Nov
12
comment How to prove that two dilations of $\mathbb R^n$ are conjugate?
Thank you, it's all clear now. It's a nice idea to choose "fundamental domains" (hadn't thought of that in this context), define the homeos there, then extend as you do. I'll keep it in mind.
Nov
12
comment How to prove that two dilations of $\mathbb R^n$ are conjugate?
Thanks! That's really what I was trying to do. Your signs are a bit odd (remember I imposed $\lambda_i>1$, what you wrote works for $\lambda_i<1$). How did you figure out how to define $h^*$?
Nov
12
comment How to prove that two dilations of $\mathbb R^n$ are conjugate?
Thank you for your answer. Could you elaborate a little bit, maybe expand on what you mean by "take logs to reduce the problem to..."?
Nov
12
accepted Does Proj induce some equivalence of categories involving graded rings?
Nov
12
accepted If $f^n$ is mixing then $f$ is mixing?
Nov
12
accepted Hartshorne, exercise II.2.18: a ring morphism is surjective if it induces a homeomorphism into a closed subset, and the sheaf map is surjective
Nov
12
accepted Does inclusion of an affine open into an affine scheme correspond to restriction?
Nov
12
asked How to prove that two dilations of $\mathbb R^n$ are conjugate?