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Apr
17
reviewed Close Intersection and Union of a random variable $X$ put in the form of $\{X\in A\}$ for an appropriate $A\subset\mathbb R$?
Apr
17
reviewed Leave Open Prove that $2n + m \equiv 0 \pmod3$if and only if $ n \equiv m \pmod3$
Apr
17
reviewed Leave Open The exceptation of a null space of a Gaussian vector is zero or not?
Apr
8
reviewed Reopen How to study math to really understand it and have a healthy lifestyle with free time?
Apr
8
reviewed No Action Needed If $K$ and $H$ are subgroups of $G$ and $H \triangleleft K$ then $K \subseteq N(H)$.
Apr
8
reviewed Leave Open Show that $\mathbb{Z}$ and $2\mathbb{Z}$ are not isomorphic as rings.
Apr
8
answered What is the difference between ring homomorphism and module homomorphism?
Mar
23
comment Prove that $|H|$ is odd and $|G/H|$ = $2^n$ for some positive integer n
Using Cauchy for 1 is overkilling! Pair elements with their inverses. Since $1_G$ is paired with itself a parity check shows immediately that there must be an other element paired with itself. For 2, yes, $\bar g=gH\in G/H$.
Mar
23
revised Prove that $|H|$ is odd and $|G/H|$ = $2^n$ for some positive integer n
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Mar
23
answered Prove that $|H|$ is odd and $|G/H|$ = $2^n$ for some positive integer n
Mar
23
awarded  Nice Answer
Mar
20
answered Show that $a - b \mid f(a) - f(b)$
Mar
20
comment Show that $a - b \mid f(a) - f(b)$
What is $f$? What are $a$ and $b$?
Mar
16
answered Is it a coincidence that $\mathbb{Z_{12}}$ has all distinct subgroups that are factors of 12?
Mar
9
awarded  Nice Answer
Mar
6
answered Relation between rank of matrix over $K$ and over $L\supset K$
Mar
6
answered Is there any hope to solve the game chess?
Mar
6
comment Are there any limit to the total amount of moves in chess?
To put that in perspective tournament chess games rarely reach move 100. In the entire history of master level chess not more than a handful games, if any, reached move 200
Mar
6
answered For every $n \in \mathbb Z^+$ , does there exist a ring automorphism $\psi$ on $\mathbb C[x]$ of order $n$?
Mar
2
revised Relationship between a vector space V and it's dual space V*
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