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seen Sep 30 at 18:58

Jul
16
accepted Sum by twos for functions on $\Bbb{Z}$
Jul
16
awarded  Commentator
Jul
16
revised Sum by twos for functions on $\Bbb{Z}$
added 11 characters in body
Jul
16
comment Sum by twos for functions on $\Bbb{Z}$
by `sum by twos' I mean exactly the thing that brogrenkp said. And I fix the error in the question.
Jul
16
revised Sum by twos for functions on $\Bbb{Z}$
edited tags
Jul
16
asked Sum by twos for functions on $\Bbb{Z}$
Jul
15
awarded  Revival
Jul
12
comment Positive Semi-Definite matrices and subtraction
@Martin Argerami: If $A=(a_{i,j})_{i,j=1}^n$ and $B=(b_{i,j})_{i,j=1}^n$ are two positive semidefinite matrices with real values and $a_{i,j}\geq b_{i,j} \geq 0$ for every $i,j$. Can we say anything about $A-B$?
Jul
7
awarded  Editor
Jul
7
revised Amenability of finite dimensional norm algebras
deleted 3 characters in body
Jul
7
accepted FC groups with infinite derived subgroup which are not constructed by direct product of finite groups.
Jul
7
comment FC groups with infinite derived subgroup which are not constructed by direct product of finite groups.
I guess in $\uparrow 12$, you mean $g_{i_1}\neq g_{j_1}$ and similarly $g_{i_k}\neq g_{j_m}$.
Jul
2
awarded  Curious
Jun
20
answered Summing $ \sum _{k=1}^{n} k\cos(k\theta) $ and $ \sum _{k=1}^{n} k\sin(k\theta) $
Jun
19
comment FC groups with infinite derived subgroup which are not constructed by direct product of finite groups.
Fair enough. I guess I should have asked for an example of FC groups which is not FD and is not decomposable as direct product of two non-trivial groups.
Jun
19
comment FC groups with infinite derived subgroup which are not constructed by direct product of finite groups.
Dear James: I am not an algebraist, so I had never seen this representation of dihedral group of order $8$. Could you just briefly explain it with respect to the usual representations of a rotation $r$ and a symmetry action $s$.
Jun
18
asked FC groups with infinite derived subgroup which are not constructed by direct product of finite groups.
Jun
11
accepted What is the answer for the $\lim\limits_{n\rightarrow \infty} \frac{\sin(nt)}{\sin(t)}$?
Jun
10
awarded  Teacher
Jun
10
comment Groups with uniform bound on the order of conjugacy classes
The proof is very beautiful and so non-trivial! Thanks.