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Jun
2
revised Center of the categories $\mathbf{Grp}$ and $\mathbf{Ab}$.
edited body
Jun
2
awarded  Revival
May
30
answered Prove $KerT=KerS, ImT=ImS$, $T \ne S$
May
29
revised two notation: semi-metric and pesudometric
added 315 characters in body
May
28
comment n-globular sets and n-categories
Unless you are talking about strict $n$-categories, there are simply too many different definitions of $n$-categories for your question to make sense.
May
28
comment What is a proof?
I'm trying to understand your objection to "a proof is just a typographical entity". Proofs using AC essentially certainly can't be considered "an algorithm or a step-by-step process...". Proofs using AC are more like a step-by-step-by-step-by-step-by-step ... (and I mean lots and lots of dots here).
May
28
comment What is a proof?
what about proofs using the axiom of choice?
May
28
comment What is a proof?
@NikosM. in mainstream mathematics non-constructive proofs are considered proofs. You interpretation is much closer to constructivism of intuitinism, branches of mathematics that demand more constructive arguments, and reject non-constructive ones. A constructivist might say that a proof is: a step-by-step process from problem statement and data to solution. However, most mathematicians are not construcitivists.
May
27
revised Why to see that $\overline{B}(x;r)$ is closed if it was just defined?
deleted 5 characters in body
May
27
answered Why to see that $\overline{B}(x;r)$ is closed if it was just defined?
May
26
answered Category Cat and set theory
May
26
answered Define subtraction for real numbers.
May
26
answered What's the difference between a partial function and a relation?
May
26
answered Confused as to why the space of all polynomials of degree at most m is a subspace of the space of polynomials
May
25
comment Trying to understand the use of the “word” pullback/pushforward.
The category of small categories is small complete and small cocomplete (though the pushouts are not trivial to construct, but they exist).
May
25
comment For all $x,y∈\Bbb{R}$ define that $ x\equiv y$ if$ x^2=y^2$
I edited your question a bit so that it starts being readable. You must wrap latex command with dollar signs (e.g., type \equiv between dollar signs to get $\equiv$). When you post a question here, you must make sure you can easily read it, so at the very least all latex command should render properly. If you can't do that, then nobody else would like to try to help you. Make and effort, and you'll see good results.
May
25
revised For all $x,y∈\Bbb{R}$ define that $ x\equiv y$ if$ x^2=y^2$
added 63 characters in body; edited title
May
25
comment Notation for dimension of vector space
I meant ${\rm dim}(V)$
May
25
comment Notation for dimension of vector space
this is certainly not a standard notation. ${\rm }(dim)(V)$ is more common. It's ok to use that notation if you make sure it is clear. I don't quite understand the rest of your question.
May
23
awarded  Nice Answer