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Space Suggestion: Realcompactification of first measurable cardinal with discrete topology

Open Moniker1998 opened this issue 11 months ago • 3 comments

Space Suggestion

Let $\nu (\kappa)$ be Hewitt realcompactification of $\kappa$ with discrete topology, where $\kappa$ is the first measurable cardinal.

Rationale

If $X$ is a Tychonoff extremally disconnected $P$-space with $|X| < \kappa$ then $X$ is discrete, yet if $X$ is discrete with $|X|\geq \kappa$ then $\nu X$ is a non-discrete extremally disconnected $P$-space. It makes sense to take the smallest example of this form.

Relationship to other spaces and properties

This space provides an example satifying the search https://topology.pi-base.org/spaces?q=tychonoff+%2B+extremally+disconnected+%2B+P-space+%2B+not+discrete

Moniker1998 avatar Jan 12 '25 21:01 Moniker1998

We might as well add first measurable cardinal with discrete topology.

Moniker1998 avatar Jan 12 '25 21:01 Moniker1998

The existence of these spaces depends on some set-theoretic assumptions beyond ZFC. In the name of such spaces, we normally put the assumption as a prefix, for example (CH). What prefix should we use in this case?

prabau avatar Jan 12 '25 23:01 prabau

Another space of this type, which is essentially strong uniform topology on $\nu(\kappa)$ above.

Moniker1998 avatar Jan 13 '25 13:01 Moniker1998