CatDat

category of Z-functors

  • notation: [CRing,Set][\mathbf{CRing}, \mathbf{Set}]
  • objects: Z-functors, i.e. functors from commutative rings to sets
  • morphisms: natural transformations
  • Related categories: Sch\mathbf{Sch}Set\mathbf{Set}

This category is used in functorial algebraic geometry. It also provides a typical example of a functor category that is not locally small, but nevertheless relevant. Most of its properties are directly derived from the category of sets, so other functor categories [C,Set][\mathbf{C}, \mathbf{Set}] for large categories C\mathbf{C} will be similar.

Properties

Properties from the database

Deduced properties

  • is finitely complete
    Since it is complete, we deduce that it is finitely complete.
  • has filtered limits
    Since it is complete, we deduce that it has filtered limits.
  • has wide pullbacks
    Since it is complete, we deduce that it has wide pullbacks.
  • has connected limits
    Since it is complete, we deduce that it has connected limits.
  • has products
    Since it is complete, we deduce that it has products.
  • has equalizers
    Since it is complete, we deduce that it has equalizers.
  • has finite products
    Since it is finitely complete, we deduce that it has finite products.
  • has countable products
    Since it has products, we deduce that it has countable products.
  • has a terminal object
    Since it has finite products, we deduce that it has a terminal object.
  • has binary products
    Since it has finite products, we deduce that it has binary products.
  • has pullbacks
    Since it has binary products and has equalizers, we deduce that it has pullbacks.
  • is connected
    Since it has a terminal object, we deduce that it is connected.
  • has coproducts
    Since it has disjoint coproducts, we deduce that it has coproducts.
  • has disjoint finite coproducts
    Since it has disjoint coproducts, we deduce that it has disjoint finite coproducts.
  • has finite coproducts
    Since it has disjoint finite coproducts, we deduce that it has finite coproducts.
  • is Cauchy complete
    Since it has equalizers, we deduce that it is Cauchy complete.
  • has sequential limits
    Since it has equalizers and has countable products, we deduce that it has sequential limits.
  • has filtered colimits
    Since it has exact filtered colimits, we deduce that it has filtered colimits.
  • is distributive
    Since it is infinitary distributive, we deduce that it is distributive.
  • has a strict initial object
    Since it is distributive, we deduce that it has a strict initial object.
  • is inhabited
    Since it is connected, we deduce that it is inhabited.
  • is balanced
    Since it is mono-regular, we deduce that it is balanced.
  • is finitely cocomplete
    Since it is cocomplete, we deduce that it is finitely cocomplete.
  • has wide pushouts
    Since it is cocomplete, we deduce that it has wide pushouts.
  • has connected colimits
    Since it is cocomplete, we deduce that it has connected colimits.
  • has coequalizers
    Since it is cocomplete, we deduce that it has coequalizers.
  • has countable coproducts
    Since it has coproducts, we deduce that it has countable coproducts.
  • has an initial object
    Since it has finite coproducts, we deduce that it has an initial object.
  • has binary coproducts
    Since it has finite coproducts, we deduce that it has binary coproducts.
  • has pushouts
    Since it has binary coproducts and has coequalizers, we deduce that it has pushouts.
  • has sequential colimits
    Since it has coequalizers and has countable coproducts, we deduce that it has sequential colimits.

Non-Properties

Non-Properties from the database

Deduced Non-Properties*

  • is not small
    Assume for a contradiction that it is small. Since it is small, we deduce that it is essentially small. Since it is essentially small, we deduce that it is locally essentially small. This is a contradiction since we already know that it is not locally essentially small.
  • is not locally small
    Assume for a contradiction that it is locally small. Since it is locally small, we deduce that it is locally essentially small. This is a contradiction since we already know that it is not locally essentially small.
  • does not have zero morphisms
    Assume for a contradiction that it has zero morphisms. Since it has zero morphisms and has an initial object, we deduce that it is pointed. Since it has a strict initial object and is pointed, we deduce that it is trivial. Since it is trivial, we deduce that it is a Grothendieck topos. Since it is a Grothendieck topos, we deduce that it is locally essentially small. This is a contradiction since we already know that it is not locally essentially small.
  • is not preadditive
    Assume for a contradiction that it is preadditive. Since it is preadditive, we deduce that it is locally essentially small. This is a contradiction since we already know that it is not locally essentially small.
  • is not additive
    Assume for a contradiction that it is additive. Since it is additive, we deduce that it is preadditive. This is a contradiction since we already know that it is not preadditive.
  • is not abelian
    Assume for a contradiction that it is abelian. Since it is abelian, we deduce that it is additive. This is a contradiction since we already know that it is not additive.
  • is not pointed
    Assume for a contradiction that it is pointed. Since it is pointed, we deduce that it has zero morphisms. This is a contradiction since we already know that it does not have zero morphisms.
  • is not locally finitely presentable
    Assume for a contradiction that it is locally finitely presentable. Since it is locally finitely presentable, we deduce that it is locally presentable. Since it is locally presentable, we deduce that it is locally essentially small. This is a contradiction since we already know that it is not locally essentially small.
  • is not locally presentable
    Assume for a contradiction that it is locally presentable. Since it is locally presentable, we deduce that it is locally essentially small. This is a contradiction since we already know that it is not locally essentially small.
  • is not locally ℵ₁-presentable
    Assume for a contradiction that it is locally ℵ₁-presentable. Since it is locally ℵ₁-presentable, we deduce that it is locally presentable. This is a contradiction since we already know that it is not locally presentable.
  • is not a Grothendieck topos
    Assume for a contradiction that it is a Grothendieck topos. Since it is a Grothendieck topos, we deduce that it is locally essentially small. This is a contradiction since we already know that it is not locally essentially small.
  • is not self-dual
    Assume for a contradiction that it is self-dual. Since it is self-dual and has a strict initial object, we deduce that it has a strict terminal object. This is a contradiction since we already know that it does not have a strict terminal object.
  • is not a groupoid
    Assume for a contradiction that it is a groupoid. Since it is a groupoid, we deduce that it is self-dual. This is a contradiction since we already know that it is not self-dual.
  • is not essentially small
    Assume for a contradiction that it is essentially small. Since it is essentially small, we deduce that it is locally essentially small. This is a contradiction since we already know that it is not locally essentially small.
  • is not thin
    Assume for a contradiction that it is thin. Since it is thin and is finitely complete, we deduce that it is Malcev. This is a contradiction since we already know that it is not Malcev.
  • is not discrete
    Assume for a contradiction that it is discrete. Since it is discrete, we deduce that it is locally small. This is a contradiction since we already know that it is not locally small.
  • is not essentially discrete
    Assume for a contradiction that it is essentially discrete. Since it is essentially discrete, we deduce that it is thin. This is a contradiction since we already know that it is not thin.
  • is not finitary algebraic
    Assume for a contradiction that it is finitary algebraic. Since it is finitary algebraic, we deduce that it is locally finitely presentable. This is a contradiction since we already know that it is not locally finitely presentable.
  • is not finite
    Assume for a contradiction that it is finite. Since it is finite, we deduce that it is small. This is a contradiction since we already know that it is not small.
  • is not essentially finite
    Assume for a contradiction that it is essentially finite. Since it is essentially finite and has finite products, we deduce that it is thin. This is a contradiction since we already know that it is not thin.
  • is not trivial
    Assume for a contradiction that it is trivial. Since it is trivial, we deduce that it is finitary algebraic. This is a contradiction since we already know that it is not finitary algebraic.
  • is not Grothendieck abelian
    Assume for a contradiction that it is Grothendieck abelian. Since it is Grothendieck abelian, we deduce that it is abelian. This is a contradiction since we already know that it is not abelian.
  • is not left cancellative
    Assume for a contradiction that it is left cancellative. Since it is left cancellative and has coequalizers, we deduce that it is thin. This is a contradiction since we already know that it is not thin.
  • is not right cancellative
    Assume for a contradiction that it is right cancellative. Since it is right cancellative and has equalizers, we deduce that it is thin. This is a contradiction since we already know that it is not thin.
  • is not split abelian
    Assume for a contradiction that it is split abelian. Since it is split abelian, we deduce that it is abelian. This is a contradiction since we already know that it is not abelian.

*This also uses the deduced properties.

Unknown properties

For these properties the database currently doesn't have an answer if they are satisfied or not. Please help to complete the data!

Special morphisms

  • Isomorphisms: natural isomorphisms
    This is true for all functor categories.
  • Monomorphisms: objectwise injective natural transformations
  • Epimorphisms: objectwise surjective natural transformations
    This holds in every functor category [C,Set][\mathcal{C},\mathbf{Set}], here applied to the case that C\mathcal{C} has just one object.