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Every Hausdorff topological space is sober, hence can be identified with a spatial locale; furthermore, every locally compact Hausdorff topological space is also Hausdorff as a locale. On the other hand, there seems to be no reason that a Hausdorff locale should have any points at all, let alone be spatial. What are some interesting examples of non-spatial Hausdorff locales?

(A Hausdorff locale is a locale $X$ such that the diagonal $\Delta : X \to X \times X$ is a closed embedding.)


Since every sublocale of a Hausdorff locale is Hausdorff, in principle it suffices to find a non-spatial sublocale of any Hausdorff locale. For example, if $K$ is an compact Hausdorff space with no isolated points, then the smallest dense sublocale of $K$ is Hausdorff but has no points. However, I am more interested in "natural" examples, especially ones where Hausdorff-ness has some extrinsic interpretation related to the construction of the example.

Zhen Lin
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Any complete atomless Boolean algebra is Hausdorff yet has no points. This is just from the identity that for any $a,b$ in a Boolean algebra, $$(a,b)=(a\wedge b,a\wedge b)\vee(a\wedge b,b\wedge\neg a)\vee(a\wedge\neg b,b)$$ and the second two pairs have meets of $0$.