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Is there a good reference for the study of locally presentable and accessible categories without the axiom of choice? For instance, it seems one will need to understand:

  1. What is a good notion of $\kappa$-small set in ZF?

  2. Do the usual definitions of $\kappa$-filtered colimit and $\kappa$-presentable object require modification?

  3. Can you still prove that a category $\mathcal K$ is of the form $\mathcal K = Ind_\kappa(\mathcal C)$ for $\mathcal C$ a small category iff $\mathcal K$ is locally small and has a small subcategory of $\kappa$-presentable objects of which every object is $\kappa$-filtered colimit?

  4. Can you still prove that $\mathcal K = Ind_\kappa(\mathcal C)$ is complete iff it is cocomplete iff (the idempotent completion of) $\mathcal C$ has $\kappa$-small colimits? Call such a $\mathcal K$ locally $\kappa$-presentable.

  5. Can you still prove the special adjoint functor theorem? I.e. that a functor between locally presentable categories is a left adjoint iff it is cocontinuous and a right adjoint iff it is accessible and continuous?

  6. --insert favorite property of accessible / locally presentable categories here --

  7. Do you need to use the word "anafunctor" to do these things properly?

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    $\begingroup$ Re 7: in all likelihood, yes. For 5 I would say you definitely need to use anafunctors. $\endgroup$
    – David Roberts
    Commented Nov 29, 2023 at 8:08
  • $\begingroup$ 5. is ready a problem with equivalences of complete preordered sets :D $\endgroup$ Commented Nov 29, 2023 at 9:41
  • $\begingroup$ @MaximeRamzi Yeah, I think this is one reason one will probably have to use anafunctors. $\endgroup$ Commented Nov 29, 2023 at 13:22
  • $\begingroup$ Doesn't it depend on whether the limits and colimits (out of which adjoints in SAFT are constructed) are given by specified functors or merely assumed to exist? It's pretty common in constructive category theory to assume that "cocomplete" means being given a colimit-assigning functor. $\endgroup$ Commented Dec 5, 2023 at 5:30

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