Limit point Definition

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July 20th 2010, 04:16 AM
mohammadfawaz

Limit point Definition

hey all,
I read the following definition of a limit in some lectures notes:
"Suppose that A⊆X (in a metric space). The point $x_0 \in X$ is a limit point of A if for every neighborhood $U(x_0, \epsilon)$ , of xo, the set $U(x_0, \epsilon)$ is an infinite set."
Well, the definition I know is: $x_0$ is a limit point of a set A if every deleted neighborhood of $x_0$ intersects A in at least one point.
Can someone explain to me the first definition? I can't make the link between the two definitions(Worried)
thanx
July 20th 2010, 04:41 AM
Plato

If $U(x_0;\epsilon)$ infinitely many points then then $U(x_0;\epsilon)\setminus\{x_0\}$ contains at least one point.

What don't you understand?
July 20th 2010, 05:01 AM
mohammadfawaz

OK, but any neighborhood $U(x_0;\epsilon)\setminus\{x_0\}$ contains at least one point anyway. It's a neighborhood. They don't mention intersection with A here! That's what I'm not getting.
thanx
July 20th 2010, 06:12 AM
Plato

Well I think the it should be understood that it is infinitely many points of A.