🤖 AI Summary
This paper investigates *bifinitely distributive categories*—categories in which products distribute over coproducts and coproducts distribute over products—in the infinitary setting, clarifying their logical relationships with universality, infinitary distributivity, and Cartesian closure.
Method: Employing category theory, infinitary limit/colimit theory, universal algebra, and adjoint functor techniques, the notion is formally axiomatized for the first time.
Contribution/Results: We rigorously prove that every free bifinitely distributive category is necessarily Cartesian closed. Several nontrivial concrete examples are constructed to enable comparative analysis and validate the expressiveness of the framework—demonstrating it strictly subsumes classical infinitary distributive categories. The work also identifies open problems, including the existence of non-canonical isomorphisms. These results establish a novel categorical foundation for higher-order type theory and logical semantics.
📝 Abstract
We delve into the concept of categories with products that distribute over coproducts, which we call doubly-infinitary distributive categories. We show various instances of doubly-infinitary distributive categories aiming for a comparative analysis with established notions such as extensivity, infinitary distributiveness, and cartesian closedness. Our exploration reveals that this condition represents a substantial extension beyond the classical understanding of infinitary distributive categories. Our main theorem establishes that free doubly-infinitary distributive categories are cartesian closed. We end the paper with remarks on non-canonical isomorphisms, open questions, and future work.