2020年4月30日木曜日

neighborhood

In general topology, a neighborhood is in a set which is opened but still closed. This is like the concept of my website.


X is the topological space, and p is the neighborhood. Moreover, U is the open set.


Therefore, V include p.

In a metric space M=(X,d), V is a set and the neighborhood of p which is the center of the open ball.


r is the radius of Br(p).