Subject: categories: Compact subsets of k-spaces (without separation axioms)

From: Gabor Lukacs <[email-masked]>
Date: Sun, 15 Feb 2004 08:47:57 -0500 (EST)

Dear Topologists, Categorists and Categorical Topologists,

It is well-known that for a *Hausdorff* topological space X, its
k-ification kX and X have the same compact subspaces.

It is also well-known that when we assume no separation axioms, X and kX
have the same k-continuous maps (i.e. maps f:X -->Y such that ft is
continuous for every "test-function" t: K --> X, where K is a compact
Hausdorff space).

I was wondering if anyone knows whether the first statement is true
*without separation axioms*, i.e., whether for every topological space X,
its k-ification kX and X have the same compact subspaces.

I would very much appreciate any suggestion, reference or counterexample.

Gabor Lukacs

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From: Martin Escardo <[email-masked]>
Date: Mon, 16 Feb 2004 10:30:23 +0000

> its k-ification kX and X have the same compact subspaces.

Sometime ago Alex Simpson advertised a paper

"Comparing cartesian closed categories of (core) compactly generated
spaces". http://www.cs.bham.ac.uk/~mhe/papers/ELS03.pdf

where we have the same question (problem 9.2). Hence if anyone has an
answer, please forward it to us as well - thanks.

(I also take the opportunity to mention that we have updated the paper
with some references given to us by some members of this list, in
Section 3.)

MHE