category of countable groups

Notation Grpc\Grp_\c Objects countable groups Morphisms group homomorphisms Related Grp\Grp, FinGrp\FinGrp, Setc\Set_\c, VectKc\Vect^\c_K

A group is called countable if its underlying set is countable. In particular, every finite group is countable, but also every finitely generated group is countable.

Satisfied Properties

Assigned properties

Deduced properties

Unsatisfied Properties

Assigned properties

Deduced properties*

*This also uses the deduced satisfied properties.

Unknown properties

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Special objects

  • terminal object: trivial group
  • initial object: trivial group
  • products: [finite case] direct products with pointwise operations
  • coproducts: [countable case] free products

Special morphisms

  • isomorphisms: bijective homomorphisms
  • monomorphisms: injective homomorphisms
  • epimorphisms: surjective homomorphisms
  • regular monomorphisms: same as monomorphisms
  • regular epimorphisms: same as epimorphisms