All Questions
3 questions
11
votes
2
answers
405
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Equivalence between geometric theories and frames internal to the free topos
What is a reference for "the equivalence between geometric theories and frames internal to the free topos"? [1] This seems to be an extremely interesting theorem.
[1] André Joyal, “A crash ...
- 35.5k
10
votes
0
answers
391
views
How do properties of a partial order $\mathbb{P}$ affect the logic of the functor category $\mathsf{Set}^\mathbb{P}$?
$\DeclareMathOperator\true{\mathsf{true}}$I am very suspicious the answer to this (family of) question(s) is well-known, but I couldn't find anything after a bit of searching so I'll ask anyway.
I am ...
- 63.9k
9
votes
1
answer
511
views
Free models of finitely presented essentially algebraic theories in elementary toposes?
The following result is well-known in folklore (I think), but I’ve been unable to find a reference in the literature:
Let $T$ be a finitely presented essentially algebraic theory, and $\newcommand{\...
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