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A shy, neither amateur nor high-class, mathematician from Colombia.


Aug
23
comment is binomial congruence given in article true or false?
That subscript $q$ stands for the so-called Gaussian binomial coefficients.
Aug
19
comment Find valuation rings of the function field $k(x,y)/k(xy)$ which do not contain $k[x,y]$.
It would be great if you put your thoughts as a complete answer.
Aug
14
reviewed Approve suggested edit on Why does this sum equal to (4^n -1)
Aug
13
reviewed Approve suggested edit on Proof that two vectors, not a scalar multiple of one another, are linearly independent
Aug
10
comment Could one make a ring of matrices of uncountable size?
I suggest you to change "uncountable matrices" by "square matrices with uncountable size" on the title.
Aug
1
reviewed Approve suggested edit on Two dice thrown, one comes up 6
Aug
1
reviewed Approve suggested edit on Does the $I$-torsion functor commute with inverse limit?
Jul
28
revised Dimension of $\dim_{\mathbb C}\mathbb C[X,Y]/I(Y^2-X^2,Y^2+X^2)$
deleted 6 characters in body
Jul
28
answered Dimension of $\dim_{\mathbb C}\mathbb C[X,Y]/I(Y^2-X^2,Y^2+X^2)$
Jul
16
comment Galois closure of $\mathbb{C}(T,\sqrt{T^2+T+1})$ over $\mathbb{C}(T^3)$
The phrasing "$\mathbb C(T)$ be a function field" is a bit misleading: by definition an algebraic function field in one variable over a field $k$ (briefly, a function field over $k$) is a finite field extension of the rational function field $k(T)$.
Jul
15
accepted Can a group with exactly five subgroups be nonabelian?
Jul
15
awarded  Citizen Patrol
Jul
7
comment The largest value of $k$ for $\Bbb{Z}^{k}$ to be embedded in $\mathcal{GL}(n,\Bbb{Z})$.
In other words, you are asking about the maximum rank of a free abelian subgroup of $\mathcal{GL}(n,\mathbb Z)$. By the way, why did you include the [finite-groups] tag?
Jul
6
comment Proving that tensoring a projective module with a flat module gives a projective module?
You are right: if $F$ is free, say $F=R^{\oplus I}$, then $M\otimes_RF$ is just $M^{\oplus I}$, which is not free in general.
Jul
3
comment Germs of $C^\infty$ functions near $0$ vs. germs of infinitely differentiable functions at $0$
@DanielFischer Thanks a lot for your partial answer.
Jul
3
revised Germs of $C^\infty$ functions near $0$ vs. germs of infinitely differentiable functions at $0$
added 52 characters in body
Jul
3
comment Germs of $C^\infty$ functions near $0$ vs. germs of infinitely differentiable functions at $0$
@DanielFischer Yes, I am interested in the algebraic properties. Regarding the complex case, you catch me, I naively thought that complex differentiability at $0$ implies differentiability of all order. I am going to edit the question.
Jul
3
revised Germs of $C^\infty$ functions near $0$ vs. germs of infinitely differentiable functions at $0$
added 219 characters in body
Jul
3
reviewed Approve suggested edit on Find the probability of selecting an ordered pair from set $S$
Jul
3
asked Germs of $C^\infty$ functions near $0$ vs. germs of infinitely differentiable functions at $0$