CatDat

countably distributive

A category is countably distributive if it has finite products, countable coproducts, and for every object $A$ the functor $A \times -$ preserves countable coproducts. Concretely, for every countable family of objects $(B_i)$ the canonical morphism $\coprod_i (A \times B_i) \to A \times \coprod_i B_i$ must be an isomorphism.

• Dual property: countably codistributive
• Related properties: countable coproducts, distributive, finite products, infinitary distributive

Relevant implications

• cartesian closed andcountable coproducts implies countably distributive
• cartesian filtered colimits andcountable coproducts anddistributive implies countably distributive
• countably codistributive andself-dual implies countably distributive
• countably distributive andself-dual implies countably codistributive
• countably distributive implies countable coproducts andfinite products
• countably distributive implies distributive
• countably distributive implies natural numbers object
• infinitary distributive implies countably distributive

Examples

There are 24 categories with this property.

• category of Hausdorff spaces
• category of locally ringed spaces
• category of M-sets
• category of measurable spaces
• category of metric spaces with continuous maps
• category of metric spaces with ∞ allowed
• category of pairs of sets
• category of posets
• category of prosets
• category of schemes
• category of sets
• category of sheaves
• category of simplicial sets
• category of small categories
• category of smooth manifolds
• category of topological spaces
• category of Z-functors
• poset [0,1]
• poset of extended natural numbers
• trivial category
• walking commutative square
• walking composable pair
• walking isomorphism
• walking morphism

Counterexamples

There are 46 categories without this property.

• category of abelian groups
• category of abelian sheaves
• category of algebras
• category of Banach spaces with linear contractions
• category of combinatorial species
• category of commutative algebras
• category of commutative monoids
• category of commutative rings
• category of fields
• category of finite abelian groups
• category of finite groups
• category of finite ordered sets
• category of finite sets
• category of finite sets and bijections
• category of finite sets and injections
• category of finite sets and surjections
• category of finitely generated abelian groups
• category of free abelian groups
• category of groups
• category of left modules over a division ring
• category of left modules over a ring
• category of metric spaces with non-expansive maps
• category of monoids
• category of non-empty sets
• category of pointed sets
• category of pointed topological spaces
• category of pseudo-metric spaces with non-expansive maps
• category of rings
• category of rngs
• category of sets and relations
• category of vector spaces
• delooping of a non-trivial finite group
• delooping of an infinite countable group
• delooping of the additive monoid of natural numbers
• delooping of the additive monoid of ordinal numbers
• discrete category on two objects
• dual of the category of sets
• empty category
• poset of natural numbers
• poset of ordinal numbers
• proset of integers w.r.t. divisibility
• simplex category
• walking fork
• walking idempotent
• walking parallel pair
• walking span

Unknown

There are 0 categories for which the database has no information on whether they satisfy this property.

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