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Jul
26
comment How is the Fourier transform a geneeralization the the Fourier series?
@Mitsos - seems that I forgot the $n$, should be ok now
Jul
26
revised How is the Fourier transform a geneeralization the the Fourier series?
edited body
Jul
26
asked How is the Fourier transform a geneeralization the the Fourier series?
Jul
24
comment Notation of an infinite union
@vadim123 - whoops, I saw to many [infinite] sums this week :P
Jul
24
revised Notation of an infinite union
deleted 216 characters in body
Jul
24
answered Notation of an infinite union
Jul
22
comment How prove : polynomial $P(x)=W^{\prime \prime}(x) +(W^\prime(x))^2$ have a real root.
How did you came up with this? What's the motivation?
Jul
17
comment For which integers $r$ is $\sigma ^r$ also a $k$-cycle?
You should at least describe your proof so someone won't repeat it
Jul
16
answered If $a^n=e$ for exactly one $a$ then show that $a\in Z(G)$
Jul
13
comment Prove that $\mathbb Z^n$ is not isomorphic to $\mathbb Z^m$ for $m\neq n$
How is it? It seems that (1,...,1) is not in the cyclic subgroup generated by this element. It seems that this cyclic subgroup is (0,...,0,Z,0,...,0)
Jul
13
comment Prove that $\mathbb Z^n$ is not isomorphic to $\mathbb Z^m$ for $m\neq n$
Can you prove the claim about the number of generators?
Jul
7
awarded  Notable Question
Jun
24
comment Worst case binary search
I'm not sure I understand, what is the data set? Is it all of [0,1]?if so it is infinite so we need to talk about that, binary search is defined for a finite collection. Also, it seems like you're thinking of searching in [0,1] with this method of eliminating halves of the interval each time, you can consider the binary representation of a number to estimate the number of steps needed for such a method
Jun
20
awarded  Popular Question
Jun
9
comment How to calculate $\log \log \log N$?
Well, how do you calculate log(N)? What is the time complexity of that? Why do you think that calculating your expression by calculating each logarithm separately is slow?
Jun
5
answered prime ideals, ring
May
24
comment An example of a group such that $G \cong G \times G$
Oh. It's displayed wrong in the mobile site
May
24
comment An example of a group such that $G \cong G \times G$
I don't understand.. If H is finite for example it's not true
May
9
comment Homomorphisms and Groups proof
@danny $f(b^{2})=f(b\cdot b)=f(b)\cdot f(b)=f^{2}(b)$ . Now use induction
May
8
answered Order of a group calculation