Structure

category of free abelian groups

Notation FreeAb\FreeAb Objects free abelian groups Morphisms group homomorphisms Related Ab\Ab, TorsFreeAb\TorsFreeAb, FreeAbfg\FreeAb_\fg
This is the full subcategory of Ab\Ab consisting of the free abelian groups. Since Z\IZ is a principal ideal domain, these coincide with the projective Z\IZ-modules, so that FreeAb≅Proj(Z)\FreeAb \cong \Proj(\IZ).

Satisfied properties

Assigned properties

Deduced properties

Unsatisfied properties

Assigned properties

Deduced properties*

*This also uses the deduced satisfied properties.

Unknown properties

—

Undecidable properties

There is 1 property for which it cannot be decided whether it is satisfied.

Special objects

  • terminal object: trivial group
  • initial object: trivial group
  • products: [finite case] direct sums
  • coproducts: direct sums

Special morphisms

  • isomorphisms: bijective homomorphisms
  • monomorphisms: injective homomorphisms
  • epimorphisms: homomorphisms f:A→Bf : A \to B with the property that f(A)f(A) is not contained in a proper direct summand of BB
  • regular monomorphisms: injective homomorphisms f:A→Bf : A \to B with the property that B/f(A)B/f(A) is free abelian (which are automatically split monomorphisms)
  • regular epimorphisms: surjective homomorphisms (which are automatically split epimorphisms)

Morphisms

The database stores 1 morphism based on the category of free abelian groups.