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location Moscow, Russia
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visits member for 4 years, 1 month
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umagon at google mail


May
14
revised Is there any group $H\times K$ where $H\times 1$ and $1\times K$ are the only subgroups of order $n$?
added the exact reference
May
12
revised Verifying Touchard's Identity
added 12 characters in body; edited tags
May
12
revised Examine the convergence of $\left({\cos n\over n}\right)$
edited title
May
11
revised Show that $x$ is an algebraic number? Where $x$ is…
deleted 4 characters in body
May
11
revised Prove: $\lim\limits_{(x,y)\to (0,0)}\frac{xy}{(x^2+y^2)^\frac12}=0$
edited title
May
8
revised How to compute the sum $\sum_{r=0}^n \frac{(-1)^r}{{n \choose r}}$
tex &c
May
7
revised When characteristic classes determine a bundle?
two examples added
May
6
revised $f(x,y)={{xy^3}\over {x+y^2}},(x,y) \ne (0,0)$ and $f(x,y)=0, (x,y)=(0,0)$
no displaymath it titles, please
May
4
revised $\operatorname{Hom}_\Lambda (B, \operatorname{Hom}_{\Bbb Z}(\Lambda, X)) = \operatorname{Hom}_\Bbb Z (B, X)$
edited tags
May
1
revised Converse of a fixed-point theorem
ref
May
1
revised Converse of a fixed-point theorem
added 521 characters in body
Apr
24
revised Is there a “natural” / “categorical” definition of the “parity” of a permutation?
a typo fixed
Apr
18
revised Topological invariance of chern classes
edited tags
Feb
7
revised Show that ${n\choose r}2^r 3^{n-r}=\sum_{k=r}^{n} {n \choose k} {k \choose r}2^k$
edited tags
Feb
2
revised How can I mathematically read this map $f:A\longrightarrow B$?
edited tags
Jan
30
revised Steenrod Algebra as automorphisms of additive group
edited tags
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
revised $1 + 1 + 1 +\cdots = -\frac{1}{2}$
edited tags
Jan
21
revised Local dimension of graph embedding
edited tags