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awarded  Caucus
Sep
25
answered On modules over simple rings
Aug
11
comment Algebraic groups of multiplicative type in char 0
Yes, this is a basic descent argument. One reference is SGA 3 Exp. IX Proposition 2.1, but there might be others that are easier for non-specialists.
Aug
11
comment Algebraic groups of multiplicative type in char 0
Any affine algebraic group is linear. This is covered near the beginning of most texts on algebraic groups.
May
14
comment Multiplication of very Large Diagonal Matrix
In the absence of structure on the diagonal entries, even reading the data takes $O(N)$ time, so I don't see how you expect a substantial improvement.
Apr
30
comment Does the pullback of a covering space correspond to the pullback of the corresponding representation of $\pi_1$?
You also want to equip your spaces with distinguished base points.
Apr
23
comment Proof that a product of two quasi-compact spaces is quasi-compact without Axiom of Choice
It looks like you are claiming that the $U$ you construct in the second paragraph is adequate, but I don't see it very clearly. In particular, there seems to be an implicit claim that $U \times X \subset W_1 \cup \cdots \cup W_n$.
Apr
16
answered What is $\lim_{n\to\infty} \displaystyle \sum_{k=0}^{\lfloor n/2 \rfloor} \binom{n}{2k}\left(4^{-k}\binom{2k}{k}\right)^{\frac{2n}{\log_2{n}}}\,?$
Apr
9
awarded  Excavator
Apr
9
awarded  Editor
Apr
9
revised In the history of mathematics, has there ever been a mistake?
Perko wrote me to request this correction.
Apr
9
suggested approved edit on In the history of mathematics, has there ever been a mistake?
Mar
12
comment On $\int_{-\infty}^{+\infty} {\frac{\tan(t-t_0)}{\cosh^2(t-t_0)} \cos(\omega t) \,\mathrm{d}t}$
How did this question arise? What have you tried?
Jan
23
comment In the history of mathematics, has there ever been a mistake?
@Zarrax Ken Perko vehemently denies having a PhD in math.
Dec
12
answered Constructible set in Gieseker's 'Lectures on Moduli of Curves'
Nov
6
awarded  Yearling
Sep
22
comment On a abelian representation of galois group
It might help to think of the Galois group as a projective limit of finite groups coming from finite Galois extensions, instead of some abstract group of automorphisms of an algebraically closed field.
Sep
17
answered Is a subring of an integral monoid ring an integral monoid ring?
Sep
10
comment Monotonic log det function?
What is $\sigma$?
Sep
10
comment Why Euler-Lagrange equation does not depend on the second derivative of the function?
See en.wikipedia.org/wiki/…