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location Buenos Aires, Argentina
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visits member for 4 years, 1 month
seen 8 hours ago

14h
comment Software or tool for investigating groups
You can say, for example, Filtered(SymmetricGroup(6), x -> x*x*x = ()); to get the list of elements of order three. I'm sure there are smarter ways :-)
16h
comment When does L' Hopital's rule fail?
You never have to compute the derivative of the function at $A$.
18h
answered Software or tool for investigating groups
19h
comment Confusion in Serre's Local fields book
My second statement is a basic result of homological algebra: one says that $\hom$ is a balanced functor because one can compute its derived functors with respect to either one of its variables. This is explained and proved in most textbooks on homological algebra. For example, see the book by Hilton and Stammbach, or Weibel's.
19h
revised Confusion in Serre's Local fields book
added 29 characters in body
19h
comment Confusion in Serre's Local fields book
Well, it is correct.
19h
answered Confusion in Serre's Local fields book
19h
comment Confusion in Serre's Local fields book
Where does he say that? It would be best if you told us exactly what he says (and where, exactly)
1d
comment Is there a theory of “rings” with partially defined multiplication?
Notice that addition is defined for all pairs of elements, and that sort of collides with the definition of ringoids.
1d
comment Is there a theory of “rings” with partially defined multiplication?
Well, the point of the question more or less clearly isto know what the full thing of Laurent series is...
1d
comment Is there a theory of “rings” with partially defined multiplication?
Inwhat way is this object a ringoid?
1d
comment Models of set theory
Mi little nephew seems to agree with you! :P
1d
comment Models of set theory
@HaraldHanche-Olsen, just as one needs to be careful not to eat the wrapping of candies!
1d
comment Prove that the ring of rational numbers $\Bbb Q$ is not isomorphic to the ring of real numbers $\Bbb R$
@AdamHughes, $\mathbb Q$ is not an $\mathbb R$-module in any way: there is no such thing as «trivially» in this context.
2d
comment topology defined on the set $\mathbb{R}^\mathbb{R}$?
well, there are many topologies on that set. What do you have in mind, exactly?
2d
comment If $\mathbb{C}[x,y]/I$ is finite dim $\mathbb{C}$-vsp, does it have a monomial basis? Related to Hilbert Scheme of points in the plane.
Every quotient of a polynomial ring has a basis of (classes of) monomials.
Aug
26
comment Solving a system of polynomial equations in three variables (x^2-yz=18, y^2-zx=8, z^2-xy=-7)
Please do not type all in caps. There is no need to use abbreviations for words: there is plenty of space, and you have the time to type everything in full. Also, your question looks like it is copied out of your homework...
Aug
25
comment Disproving an “almost true” trigonometric identity
One can prove the irreducibility of the cyclotomic polynomials without making recourse to ramification, as in Lang' Algebra (Thenargument goes back to Dirichlet, iirc)
Aug
25
comment Why is there no natural metric on manifolds?
It should be mentioned that (for an appropriate meaning of the words, which is a rather subtle point) in dimension 2 and 3, (most) manifolds do have certain metrics which are in a sense natural. This is classic for surfaces and Thurston's geometrization program (whose proof was completed by Perelman) for dimension 3.
Aug
25
comment Some questions about homology with local coefficients.
I cannot parse your 3rd paragraph. Restricting what functor to what automorphism group of $x$? What are the two different ways you mention? In your 4th paaragraph: which are the first complex? the one you described in your 1st paragraph?