In many extensive categories, the current proof that they are extensive, is only sketched (such as for manifolds). It would be nice to write down the details and/or give a proper reference. The idea is of course always to reduce it to the category of sets somehow. Probably we can formulate a lemma of the form "If C -> D is a nice functor and D is extensive, then C is extensive as well".
This issue has been created by Martin via the submission form on https://catdat.app/category/Man
In many extensive categories, the current proof that they are extensive, is only sketched (such as for manifolds). It would be nice to write down the details and/or give a proper reference. The idea is of course always to reduce it to the category of sets somehow. Probably we can formulate a lemma of the form "If C -> D is a nice functor and D is extensive, then C is extensive as well".
This issue has been created by Martin via the submission form on https://catdat.app/category/Man