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math.CT2026
Effective quasi-Polish categories of overt discrete spaces and compact Hausdorff spaces
Matthew de Brecht
We construct the category of overt discrete quasi-Polish spaces and the category of compact Hausdorff quasi-Polish spaces (and some of their subcategories) as internal categories o…
math.LO2026
On the completeness of the countable fragment of geometric logic
Matthew de Brecht
We give self contained proofs of the completeness of countable -coherent theories, for both propositional and predicate logic. By -coherent logic we mean the fragment of geom…
math.LO2026
A note on computable étale spaces
Matthew de Brecht
An étale space over a topological space is defined as a local homeomorphism from a topological space into . They often come up in topos theory because of the equivalence…