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location Moscow, Russia
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visits member for 3 years, 9 months
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umagon at google mail


Jan
29
reviewed Close Limit of Series with Variable Lower Bound
Jan
29
reviewed Close Question from Marker's book T3 has three models up to isomorphism
Jan
27
reviewed Close About mixed strategy Nash Equilibrium
Jan
25
comment Proving that $\left(\frac{\pi}{2}\right)^{2}=1+\sum_{k=1}^{\infty}\frac{(2k-1)\zeta(2k)}{2^{2k-1}}$.
None of downvotes are mine, but how exactly 'this series admits this integral representation — prove it yourself' is any better than 'this series is equal to $\pi^2/4-1$ — prove it yourself'? Maybe experts can see what you're alluding too, but this answer hasn't taught me anything, I'm afraid (and, AFAICS, other users haven't found this helpful either).
Jan
25
revised Quarternionic Analysis
edited tags
Jan
24
revised On solving $\sqrt{2+\sqrt{2+\sqrt{2+\sqrt{2+x}}}}=\sqrt[3]{6+\sqrt[3]{6+\sqrt[3]{6+\sqrt[3]{6+x}}}}$
edited tags
Jan
23
comment $1 + 1 + 1 +\cdots = -\frac{1}{2}$
Related: math.stackexchange.com/q/39802 (and links there)
Jan
23
revised $1 + 1 + 1 +\cdots = -\frac{1}{2}$
edited tags
Jan
23
comment Is there a connected topology space that is disconnected by remove any point?
Related: math.stackexchange.com/q/634787
Jan
23
comment How do I see that $x^5+x-1=(x^2-x+1)(x^3+x^2-1)$
$x^2(x+1)A-A=(x^3+x-1)A$. What is your question?
Jan
21
revised Local dimension of graph embedding
edited tags
Jan
21
comment Double categories
Related: ncatlab.org/nlab/show/double+category
Jan
21
reviewed Close Let $f:\mathbb{R}\rightarrow\mathbb{R}$ be multiplicative. Is it exponential?
Jan
20
reviewed Close the product space $\mathbb{R}^I$,where I denote $[0,1]$, has a countable dense subset.
Jan
20
comment What comes after $\cos(\tfrac{2\pi}{7})^{1/3}+\cos(\tfrac{4\pi}{7})^{1/3}+\cos(\tfrac{6\pi}{7})^{1/3}$?
I'm not sure there exists a (good) generalization in this direction — but maybe you'll find another generalization of the second formula of interest
Jan
19
revised cohomological-operations wiki excerpt
added 211 characters in body
Jan
19
wiki created cohomological-operations excerpt
Jan
19
suggested suggested edit on cohomological-operations tag wiki excerpt
Jan
19
comment Ramanujan-type trigonometric identities with cube roots, generalizing $\sqrt[3]{\cos(2\pi/7)}+\sqrt[3]{\cos(4\pi/7)}+\sqrt[3]{\cos(8\pi/7)}$
(The question is quite long already, but maybe I'll add some thoughts/comments later...)
Jan
19
comment Why does $1+2+3+\dots = {-1\over 12}$?
See also Infinite series are weird blog post