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4 questions
11
votes
1
answer
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Are flat functors out of a finite category necessarily finite?
Note: I've originally asked this question on math stack exchange, but I have learnt that this is the better place to ask for research level questions, so I have deleted the original question there.
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- 499
13
votes
1
answer
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Model existence theorem in topos theory
One of most classical and somehow striking result in classical model theory states:
A consistent first order theory $T$ has a model.
Few considerations are needed.
This result is not true for ...
- 2,221
26
votes
2
answers
2k
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Precise relationship between elementary and Grothendieck toposes?
Elementary toposes form an elementary class in that they are axiomatizable by (finitary) first-order sentences in the "language of categories" (consisting of a sort for objects, a sort for morphisms, ...
- 55
2
votes
0
answers
392
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Geometric Theories have models in any Grothendieck Topos?
This question is linked to this one.
My question is:
Is it true any consistent geometric (here I mean coherent theory, different books have different standards) theory $T$ has a model in a ...
- 9,111