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Aug
12
revised Characters appearing naturally in arithmetic functions
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Aug
12
asked Characters appearing naturally in arithmetic functions
Aug
12
revised From 4 squares to 2 squares
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Aug
12
asked From 4 squares to 2 squares
Aug
9
comment A Combinatorial Proof of Dixon's Identity
Thanks, @darijgrinberg! It's a good article to display the diversity of techniques for proving combinatorial identites.
Jun
20
revised Number of solutions of $x^2_1+\dots+x^2_n=0,$ $x_i\in \Bbb{F}_q.$
fixed sign mistakes
Jun
3
comment From Tilings To Groups
(cont.) To get full understanding one should see what Gromov's motivation was for the word-hyperbolic definition, and read his books. I guess the theorem you mentioned will make an appearance there.
Jun
3
comment From Tilings To Groups
Thanks. I'll go on reading about this theorem (does it have a name, btw?). I've already seen the notion of quasi-isometry and its relation to Cayley graphs (actually, the primer also includes the $\delta$ definition of hyperbolicity). The more I read, the more I understand that the word-hyperbolic def. is useful for proving some theorems (say, "Density 1/2" of Gromov, which I recommend reading), but is not the most intuitive and especially not the most geometric.
Jun
3
accepted From Tilings To Groups
Jun
3
revised From Tilings To Groups
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Jun
3
revised From Tilings To Groups
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Jun
3
asked From Tilings To Groups
May
11
awarded  Nice Answer
May
1
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Apr
11
comment Can someone please explain the Riemann Hypothesis to me… in English?
Can anyone provide a free link to the first linked paper?
Apr
1
comment Lucas's Cyclotomic Formula
Cool, thanks, I've missed that. So, essentially, one uses the identity $\phi_n(x^2) = \phi_n(x) \phi_n(-x)$ (valid for relevant $n$'s) and applies the Gauss identity for $\phi_n$ to get the Lucas identity (with $x^2$ in place of $x$). One needs to prove some properties of $R,S$ in Gauss identity, I might fill in the details in an answer later.
Apr
1
comment Lucas's Cyclotomic Formula
@DietrichBurde Maybe I can, but I didn't find the way. Care to elaborate?
Apr
1
asked Lucas's Cyclotomic Formula
Apr
1
answered This limit: $\lim_{n \rightarrow \infty} \sqrt [n] {nk \choose n}$.
Apr
1
revised Finding the limit of $\sqrt[n]{{kn \choose n}}$
merged 2 answers