Sign up ×
MathOverflow is a question and answer site for professional mathematicians. It's 100% free, no registration required.

Hello !

If I'm not mistaken, an atomic topos decompose as a disjoint sum of connected atomic topos, and Connected Atomic topos with a point corresponds to classifying topos of localic groups.

But what about conected atomic topos without point ? do we know what they look like ?

I actually know no example of these non-spatial atomic topos. So if a 'classification' of them is not possible, any example will already be interesting.

Thank you !

share|cite|improve this question
There is an example of a pointless connected atomic topos: see Example 3.4.14 in [Sketches of an elephant, Part D]. – Zhen Lin Jun 18 '13 at 22:13
I added the [ct.category-theory] tag. – David Roberts Jun 18 '13 at 22:33
@Zhen - why not add that as an answer, or even better, write it out? Not everyone has access to the Elephant (it does cost a small fortune after all). – David Roberts Jun 18 '13 at 22:34
I would if I understood the construction myself! – Zhen Lin Jun 18 '13 at 22:52
@David, concerning Elephants, contact me. I don't seem to have your current email address. – Urs Schreiber Jun 18 '13 at 23:15

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.