3,148 reputation
11036
bio website bruno.stonek.com
location Montevideo, Uruguay
age 23
visits member for 2 years, 7 months
seen yesterday
stats profile views 717

Math student in Universidad de la República, Montevideo, Uruguay.


May
17
comment When quotient map is open?
Another sufficient condition: that the map be a surjective submersion of smooth manifolds.
May
10
comment Evaluate $\int_0^{\pi \over 3} \sec x\tan x\sqrt {\sec x + 2} \, dx $ using a substitution of your choice
Please don't use \limits on the title of a question: it doesn't render prettily on the main page. Thanks.
May
10
revised Evaluate $\int_0^{\pi \over 3} \sec x\tan x\sqrt {\sec x + 2} \, dx $ using a substitution of your choice
edited title
May
6
awarded  Caucus
Apr
29
awarded  Notable Question
Apr
21
comment Why is the determinant equal to the index?
For a self-contained proof of this theorem, see theorem 1.17 in Stewart & Tall's Algebraic Number Theory (3rd. ed).
Apr
17
comment There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
Oh, I see you wrote \not\perp but somehow I see it rendered as $\perp$. I'll reread your answer then.
Apr
16
comment There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
Ok, I finished grasping your answer, I like it, it's slick :) Thank you.
Apr
16
comment There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
I can certainly empathize with that :) But in this case $n$ will be the dimension of a manifold, and $k$ the dimension of the ambient space it sits in.
Apr
16
comment There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
I think you mean that the matrix has rank $n$, as $n\leq k$, so you select $n$ linearly independent rows...
Apr
16
comment There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
@MarcvanLeeuwen: yes, I mean isomorphism of plain vector spaces. I don't think the inner product is irrelevant, how do you make sense of the orthogonal projection if it isn't there?
Apr
16
revised There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
added 77 characters in body
Apr
16
answered Is vector subtraction commutative?
Apr
16
revised Is vector subtraction commutative?
deleted 2 characters in body; edited title
Apr
16
comment There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
I think I don't understand your argument. Why can you choose $i_1$ such that $e_{i_1}\perp W$? The same example you gave on your comment to my answer is a counterexample.
Apr
16
comment There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
@Berci: shame on me, of course, you're right.
Apr
16
answered Lie bracket of vector fields and differential of diffeomorphism in its definition
Apr
16
comment There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
Thank you for your answer! While riding back home on the bus today I found a similar argument, I believe, which I think is easier to justify by reductio ad absurdum. Would you care to look at it? Perhaps you can help me with the combinatorial argument :)
Apr
16
answered There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
Apr
15
revised There is an orthogonal projection of a subspace onto a canonical subspace that is an isomorphism
edited title