Monday, March 14, 2011

??i'm getting confused here about stuff like ... ???how idea that [quasicoherent sheaves are sheaves with a certain special property... rather than just arbitrary module objects over the ring object ... ??/or something... and so forth ...] relates to idea that [??(2,1)-colimits of ag theories (and/or of tag theories?? ... and so forth ....) get along nicely with "pasting together" of varieties (resp toric varieties)] ... ??? .... ?????? .....

???something about ... how module ag theory of ringed topos gets along with "pasting together" of ringed toposes ... ???and so forth ... ???.....

??hmmm.... ??something about certain questions that martin was asking me about semi-recently ... ???..... ??something about geometric pullback of schemes, and how it gets along with ag theories of quasicoherent schemes ... ??or something, and so forth ... ???but something about "pasting" was getting involved as well ... ???....

??so again, let's consider nice simple example of non-quasicoherent sheaf ... ???...

??something about ... ???non-quasicoherent sheaf over _affine_ scheme ... ??? ... ??? ...

???something about quasicoherence as one of those properties that's essentially saying something about localness wrt point of base space rather than of total space ??? ... ??? .....

??as opposed to mere sheaf of modules ... ??...

??so what about a sheaf of sets st the free module on it is quasicoherent ??? .... and so forth ... ???....

???something about ... "locally [isomorphic to sheaf of modules coming from global module] ..." vs "locally [having global sections isomorphic to those of a global module] ... " .... ???.... ??the latter being pretty much vacuous?? ... and so forth ...

??something about... ??idea of definition of "quasicoherent sheaf" as designed precisely so as to make colimits of schemes correspond to (??(2,1)- ... or something ...)colimits of their quasicoherent sheaf ag theories ?? ???... or something ... ??... ?????.....

??i mean... something about ... ??in such a way as to generalize the affine case, or something ... ???? ....

??something about kan extension of (2,1)-functor "module ag theory of comm ring" along yoneda embedding ??? .... and so forth ...

???what was that question that i posted to n-lab, exactly ???.... ben-zvi gave a partial answer ... ???..... ???something about colimits of _schemes_ ... and so forth ...

??something about "toric case", and so forth ... ??

??something about... ???how this relates to "spectrum of ag theory" and so forth ... ???.... ????something about ... ???vague "galois connection" idea here ?????? .... ???or something ??? .... ???hmm, how literally ???? .... ????....

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