bio | website | topologia-geral.ourproject.or… |
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location | Brasília - Brasil | |
age | 36 | |
visits | member for | 2 years, 10 months |
seen | yesterday | |
stats | profile views | 341 |
PhD student at UnB.
Fond of free software and freedom of knowledge. :-)
You can contact me at:
andre.em.caldas@gmail.com
Aug 10 |
awarded | Nice Question |
Mar 28 |
awarded | Popular Question |
Nov 18 |
awarded | Nice Question |
Sep 30 |
awarded | Yearling |
Apr 4 |
awarded | Necromancer |
Jan 3 |
comment |
Supremum amongst Kolmogorov-Sinai entropies: ergodic or just invariant measures.
How do you prove that $\mu(X) = 1$ implies $m(X) = 1$ for $\tau$-a.e. $m$? Remember that having an "ergodic decomposition" means that for every continuous $\phi: \widetilde{X} \to \mathbb{R}$, $\int \phi d\mu = \int_{E(T)} \int \phi dm d\tau$. Also, notice that it might happen that $X \neq T^{-1}X$. |
Oct 13 |
revised |
locally connected versus locally compact
Fixed math statement. |
Oct 13 |
comment |
locally connected versus locally compact
This is a very neat way to justify my intuitive but not so elaborate and well justified belief that any neighborhood should have the property. Note taken! :-) I think of a neighborhood as a "sufficiently large set". Large enough to be considered a neighborhood. Often, one needs to choose a "small" set, but at the same time, big enough to make the small step big enough to achieve the goal... "path connect two points", for instance. |
Oct 13 |
comment |
Infinite dimensional vector spaces with compact unit ball
I liked your question, Leandro! I had never thought of $\mathbb{R}$ as a infinite dimensional space with compact unit ball! You opened my mind a bit! :-) +1 |
Oct 13 |
comment |
locally connected versus locally compact
Which one is your "standard 'locally <blank>' definition"? :-) |
Oct 13 |
answered | locally connected versus locally compact |
Oct 11 |
comment |
Extending open maps to Stone-Cech compactifications
The extension is unique, are you just asking if the extension is or not an open surjection? |
Oct 9 |
accepted | Compact group extension of a zero entropy system. |
Oct 7 |
comment |
Compact group extension of a zero entropy system.
@Asaf: Thank you very much for the help. I will study your answer. :-) |
Oct 5 |
comment |
Compact group extension of a zero entropy system.
By the way, a similar argument to "Lemma 7" is used in Theorem 2.3 of "On Li-Yorke Pairs": imath.kiev.ua/~skolyada/LY.pdf "Since an isometric extension of a zero-entropy system has still entropy zero [...]" |
Oct 5 |
comment |
Compact group extension of a zero entropy system.
@Asaf: Oops... (again!) Sorry for not paying the attention you deserve! Theorem 8.2 reads: If $(X, \mathcal{B}, \mu, T)$ is an ergodic isometric extension of $(Y, \mathcal{D}, \nu, T)$ then $(X, \mathcal{B}, \mu, T)$ is a factor of an ergodic group extension of $(Y, \mathcal{D}, \nu, T)$. In Furstenberg's paper, the definition for isometric extensions is quite complicated, but there is a comment (p. 236) saying: Extensions for which $\mathcal{E}(X|Y,T) = L^2(X)$ will be called isometric extensions. |
Oct 5 |
revised |
Compact group extension of a zero entropy system.
Changed the measure to be ergodic. |
Oct 5 |
comment |
Compact group extension of a zero entropy system.
@Asaf: I will have to study a bit more to fully understand your comments... :-) I guess I am forgetting the fact that $\mu$ is supposed to be ergodic. I will edit (again!) the post. By the way, I am trying to make sense of the demonstration of Lemma 7 at math.u-psud.fr/~ruette/articles/asympent.pdf |
Oct 5 |
revised |
Compact group extension of a zero entropy system.
Fixed: Elements of K are supposed to be measure-preserving. |
Oct 5 |
comment |
Compact group extension of a zero entropy system.
@Asaf: Oops... you are right. It is a very good example. I will fix the post. |