Example 5.8.12 (0B35)—The Stacks project

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Example 5.8.12. Let $Z$ be an infinite set and let $z\in Z$ . We furnish $Z$ with the topology whose closed sets are $Z$ and the finite subsets of $Z\setminus \{ z\}$ . Then $Z$ is sober but its subspace $Z\setminus \{ z\}$ is not quasi-sober.

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Comment #3545 by Laurent Moret-Bailly on August 27, 2018 at 14:41

Just a suggestion on the "set difference" notation: the \smallsetminus command produces $X\smallsetminus Y$ , which I think is better that $X\setminus Y$ (the latter is indistinguishable from a quotient by a left action).

Comment #3677 by Johan on October 22, 2018 at 10:29

OK, I never knew about this command... but it turns out it isn't in the latex packages we use in the Stacks project... I've been traditionally hesitant to load more packages than absolutely needed... If more people second your suggestion then I'll make the change globally.

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