Metric =
https://mathworld.wolfram.com/Metric.html
{ (2023-10-23)
A nonnegative function
$\displaystyle g(x,y)$ describing the "
거리,distance" between neighboring points for a given
집합,set. //
근방,neighborhood? 아님 그냥 가까이 있다는 표현?
A
metric satisfies the
삼각부등식,triangle_inequality
$\displaystyle g(x,y)+g(y,z)\geq g(x,z)$ (1)
and is symmetric, so //
대칭성,symmetry이 있음
$\displaystyle g(x,y)=g(y,x).$ (2)
A
metric also satisfies
$\displaystyle g(x,x)=0,$ (3)
as well as the condition that
$\displaystyle g(x,y)=0$ implies
$\displaystyle x=y.$ If this latter condition is dropped, then
$\displaystyle g(x,y)$ is called a
pseudometric instead of a
metric.
// 즉 (1) (2) 두 가지만 만족하면 pseudometric -
pseudometric pseudometric pseudometric