Cartesian products of abelian groups

Content created by Jonathan Prieto-Cubides, Egbert Rijke and Fredrik Bakke.

Created on 2022-05-21.
Last modified on 2023-03-13.

module group-theory.cartesian-products-abelian-groups where
open import foundation.dependent-pair-types
open import foundation.equality-cartesian-product-types
open import foundation.identity-types
open import foundation.sets
open import foundation.universe-levels

open import group-theory.abelian-groups
open import group-theory.cartesian-products-groups
open import group-theory.groups
open import group-theory.monoids
open import group-theory.semigroups


The cartesian product of two abelian groups A and B is an abelian group structure on the cartesian product of the underlying sets.


module _
  {l1 l2 : Level} (A : Ab l1) (B : Ab l2)

  group-prod-Ab : Group (l1  l2)
  group-prod-Ab = prod-Group (group-Ab A) (group-Ab B)

  monoid-prod-Ab : Monoid (l1  l2)
  monoid-prod-Ab = monoid-Group group-prod-Ab

  semigroup-prod-Ab : Semigroup (l1  l2)
  semigroup-prod-Ab = semigroup-Group group-prod-Ab

  set-prod-Ab : Set (l1  l2)
  set-prod-Ab = set-Group group-prod-Ab

  type-prod-Ab : UU (l1  l2)
  type-prod-Ab = type-Group group-prod-Ab

  is-set-type-prod-Ab : is-set type-prod-Ab
  is-set-type-prod-Ab = is-set-type-Group group-prod-Ab

  add-prod-Ab : (x y : type-prod-Ab)  type-prod-Ab
  add-prod-Ab = mul-Group group-prod-Ab

  zero-prod-Ab : type-prod-Ab
  zero-prod-Ab = unit-Group group-prod-Ab

  neg-prod-Ab : type-prod-Ab  type-prod-Ab
  neg-prod-Ab = inv-Group group-prod-Ab

  associative-add-prod-Ab :
    (x y z : type-prod-Ab) 
    Id (add-prod-Ab (add-prod-Ab x y) z) (add-prod-Ab x (add-prod-Ab y z))
  associative-add-prod-Ab = associative-mul-Group group-prod-Ab

  left-unit-law-add-prod-Ab :
    (x : type-prod-Ab)  Id (add-prod-Ab zero-prod-Ab x) x
  left-unit-law-add-prod-Ab = left-unit-law-mul-Group group-prod-Ab

  right-unit-law-add-prod-Ab :
    (x : type-prod-Ab)  Id (add-prod-Ab x zero-prod-Ab) x
  right-unit-law-add-prod-Ab = right-unit-law-mul-Group group-prod-Ab

  left-inverse-law-add-prod-Ab :
    (x : type-prod-Ab)  Id (add-prod-Ab (neg-prod-Ab x) x) zero-prod-Ab
  left-inverse-law-add-prod-Ab = left-inverse-law-mul-Group group-prod-Ab

  right-inverse-law-add-prod-Ab :
    (x : type-prod-Ab)  Id (add-prod-Ab x (neg-prod-Ab x)) zero-prod-Ab
  right-inverse-law-add-prod-Ab = right-inverse-law-mul-Group group-prod-Ab

  commutative-add-prod-Ab :
    (x y : type-prod-Ab)  Id (add-prod-Ab x y) (add-prod-Ab y x)
  commutative-add-prod-Ab (pair x1 y1) (pair x2 y2) =
    eq-pair (commutative-add-Ab A x1 x2) (commutative-add-Ab B y1 y2)

  prod-Ab : Ab (l1  l2)
  pr1 prod-Ab = group-prod-Ab
  pr2 prod-Ab = commutative-add-prod-Ab

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