Tagged Questions
4
votes
2answers
238 views
What is a Neighborhood?
Which of these definitions is more commonly used, and in which contexts?
Fix a point $x\in (X, \tau)$. Then a neighborhood around a point $x$ is:
a set $N\ni x$ and $N\in \tau$
a set $N$ with $x\in ...
6
votes
3answers
525 views
What does a “convention” mean in mathematics?
We all know that $0!=1$, the degree of the zero polynomial equals $-\infty$, the interval$[a,a)=(a,a]=(a,a)=\emptyset$ ... and so on, are conventions in mathematics. So is a convention something that ...
1
vote
1answer
99 views
Instantiate spaces in commutative diagram by “appropriate” elements - name of this idea?
I wonder whether the following concept has a name.
Suppose you are given a commutative diagram $\mathcal C$, that we think of a small category where each hom-class (i.e. hom-set) consists of at most ...
