General topology question
- From: "Julien Santini" <julien_santini@xxxxxxxxx>
- Date: 14 Jul 2005 14:30:32 -0700
Hello,
I'm reading Hocking & Young's topology again and I've hit upon a kind
of suspect assertion:
"If S is a countably compact T_i space, and f: S->T is continuous and
onto, consider an infinite subset X of T. For each point x in X, select
a point y in S such that f(y) = x. The set of all such points y is an
infinite set Y in S and hence has a limit point p. Continuity then
implies that every open set in T containing f(p) also contains
infinitely many points of X. Thus X has a limit point in T".
I would say the assertion is true only for i>=1. Also, the point of the
theorem is to show that a continuous function maps a countably compact
space onto a countably compact space, and the T_i hypothesis seems
unnecessary. Am I wrong ??
--
Julien Santini
.
- Follow-Ups:
- Re: General topology question
- From: Stuart M Newberger
- Re: General topology question
- Prev by Date: Re: Looking for Linear Stretch Constant for 1D Function
- Next by Date: Is there a name for this?
- Previous by thread: Re: Quieres ganar Dinero (fasil, rapido y legal). Te apetece.?
- Next by thread: Re: General topology question
- Index(es):
Loading