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answered How to divide by a matrix
Jul
13
comment Prove that $\mathbb Z^n$ is not isomorphic to $\mathbb Z^m$ for $m\neq n$
IMHO, you should make clear that your "Generalization" is a generalization of the fact, not of the "Second proof", as $\Bbb Q$ is not a quotient field of $\Bbb Z$. As it stands, the Second proof generalizes immediately to a domain $A$ by taking its field of quotients.
Jul
12
awarded  Nice Answer
Jul
12
answered How to explain your area of study to non-math people
Jul
12
comment How to explain your area of study to non-math people
I guess that If you are applying for a grant and your interviewer is not a mathematician your enjoyment will be very short-lived
Jul
7
comment Example of finitely generated Z[x]-module which is not a direct sum of cyclic modules
@user26857, me too. And, by the way, a non-principal ideal in a domain $R$ is never free as a $R$-module because the product of any choice of subset of generators is a non-zero element in the intersection of the modules they generate singularly. This is precisely the argument given in my answer.
Jul
7
comment Example of finitely generated Z[x]-module which is not a direct sum of cyclic modules
@user26857 : you mean that I have to do all the work?
Jun
29
comment Is it possible for a strategy game like paper, scissor rock to exist?
Define luck ...
Jun
28
comment (Is it a set?) Set of all months having more than 28 days.
@AsafKaragila: I am not so sure about your claim. Is the "set" of questions published in Math StackExchange not a set? A standard exercise for first year Algebra students is to compute the number of possible necklaces made of identical stones of different colors: this is done applying the Burnside formula to the dihedral group acting on the set of all necklaces. Does that mean that necklaces are mathematical objects?
Jun
27
revised (Is it a set?) Set of all months having more than 28 days.
deleted 39 characters in body
Jun
26
comment (Visual) Intuition: Division and complex fractions
Duplicate of math.stackexchange.com/questions/1339927/… ?
Jun
26
answered (Is it a set?) Set of all months having more than 28 days.
Jun
26
answered Why do we switch the denominator and numerator when we divide fractions?
May
25
comment Let $a,x \in \mathbb{Z}$ and $n \in \mathbb{N}$, suppose $ax \equiv 1 \mod n$. Prove $a$ is coprime to $n$.
I.e. $ax-nk=1$. Check en.wikipedia.org/wiki/B%C3%A9zout%27s_identity
May
12
comment Prove that the unit ball in $X$ is not compact
@MeesdeVries: Absolutely. Edited, thank you.
May
12
revised Prove that the unit ball in $X$ is not compact
added 15 characters in body
May
12
answered Prove that the unit ball in $X$ is not compact
May
11
comment Proving function is $C^k$
Note that when $n=1$, $f$ even means that $f(x)=f(\mid x\mid)$.
May
11
answered Multiplication modulo 10 in Cayley's Table
May
11
comment Multiplication modulo 10 in Cayley's Table
You are. This is the table of the multiplication between invertible integers mod 10