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Sep 24, 2015 at 20:37 comment added Ingo Blechschmidt @ChristopherTownsend, that claim of Peter is discussed on the nForum, with no clear consensus. One thing to note is that the "pullback square" in question only commutes up to a non-invertible natural transformation.
Apr 12, 2013 at 16:26 answer added Sean Tilson timeline score: 3
Feb 28, 2012 at 9:01 vote accept Christopher Townsend
Feb 28, 2012 at 9:01
Feb 28, 2012 at 9:01 vote accept Christopher Townsend
Feb 28, 2012 at 9:01
Feb 28, 2012 at 9:01 vote accept Christopher Townsend
Feb 28, 2012 at 9:01
S Feb 28, 2012 at 9:01 vote accept Christopher Townsend
Feb 28, 2012 at 9:01
Feb 28, 2012 at 9:01 vote accept Christopher Townsend
S Feb 28, 2012 at 9:01
Feb 28, 2012 at 9:01 comment added Christopher Townsend @Peter Arndt, I thought through what you said. Viewing rings as geoemtric morphisms, I can't see how every affine scheme can be a pullback of toposes as described. The morphism being pulled back is a subtopos morphism from one classifying topos(that of local rings) to another (that of rings). It's pullback will be a subtopos of Set, and these correspond [I think] to sublocales of 1 and not to coherent locales in general, which they must for the caracterization to work. I am sure you are right, but perhaps you can see my difficult in agreeing the characterisation?
Feb 24, 2012 at 1:10 answer added Anton Fetisov timeline score: 0
Feb 23, 2012 at 21:51 comment added Peter Arndt An affine scheme is a ringed topos arising as a pullback of topoi, namely as the pullback of a morphism from the topos of sets to the classifying topos of rings along the forgetful morphism from the classifying topos of local rings to the topos of rings - see this answer for more details: mathoverflow.net/questions/8204/…
Feb 23, 2012 at 14:26 answer added Martin Brandenburg timeline score: 10
Feb 23, 2012 at 12:56 comment added Zhen Lin In terms of pure point set topology, there is a complete characterisation of spectral spaces.
Feb 23, 2012 at 9:54 answer added Mark Grant timeline score: 10
Feb 23, 2012 at 9:29 answer added Sasha timeline score: 19
Feb 23, 2012 at 9:07 history asked Christopher Townsend CC BY-SA 3.0