Dependent products of semirings

Content created by Egbert Rijke and Fredrik Bakke.

Created on 2023-03-13.
Last modified on 2023-03-19.

module ring-theory.dependent-products-semirings where
open import foundation.dependent-pair-types
open import foundation.function-extensionality
open import foundation.identity-types
open import foundation.sets
open import foundation.universe-levels

open import group-theory.commutative-monoids
open import group-theory.dependent-products-commutative-monoids
open import group-theory.dependent-products-monoids
open import group-theory.monoids
open import group-theory.semigroups

open import ring-theory.semirings


Given a family of semirings R i indexed by i : I, their dependent product Π(i:I), R i is again a semiring.


module _
  {l1 l2 : Level} (I : UU l1) (R : I  Semiring l2)

  additive-commutative-monoid-Π-Semiring : Commutative-Monoid (l1  l2)
  additive-commutative-monoid-Π-Semiring =
    Π-Commutative-Monoid I
      ( λ i  additive-commutative-monoid-Semiring (R i))

  semigroup-Π-Semiring : Semigroup (l1  l2)
  semigroup-Π-Semiring =
    semigroup-Commutative-Monoid additive-commutative-monoid-Π-Semiring

  multiplicative-monoid-Π-Semiring : Monoid (l1  l2)
  multiplicative-monoid-Π-Semiring =
    Π-Monoid I  i  multiplicative-monoid-Semiring (R i))

  set-Π-Semiring : Set (l1  l2)
  set-Π-Semiring =
    set-Commutative-Monoid additive-commutative-monoid-Π-Semiring

  type-Π-Semiring : UU (l1  l2)
  type-Π-Semiring =
    type-Commutative-Monoid additive-commutative-monoid-Π-Semiring

  is-set-type-Π-Semiring : is-set type-Π-Semiring
  is-set-type-Π-Semiring =
    is-set-type-Commutative-Monoid additive-commutative-monoid-Π-Semiring

  add-Π-Semiring : type-Π-Semiring  type-Π-Semiring  type-Π-Semiring
  add-Π-Semiring =
    mul-Commutative-Monoid additive-commutative-monoid-Π-Semiring

  zero-Π-Semiring : type-Π-Semiring
  zero-Π-Semiring =
    unit-Commutative-Monoid additive-commutative-monoid-Π-Semiring

  associative-add-Π-Semiring :
    (x y z : type-Π-Semiring) 
    add-Π-Semiring (add-Π-Semiring x y) z 
    add-Π-Semiring x (add-Π-Semiring y z)
  associative-add-Π-Semiring =
    associative-mul-Commutative-Monoid additive-commutative-monoid-Π-Semiring

  left-unit-law-add-Π-Semiring :
    (x : type-Π-Semiring)  add-Π-Semiring zero-Π-Semiring x  x
  left-unit-law-add-Π-Semiring =
    left-unit-law-mul-Commutative-Monoid additive-commutative-monoid-Π-Semiring

  right-unit-law-add-Π-Semiring :
    (x : type-Π-Semiring)  add-Π-Semiring x zero-Π-Semiring  x
  right-unit-law-add-Π-Semiring =
    right-unit-law-mul-Commutative-Monoid additive-commutative-monoid-Π-Semiring

  commutative-add-Π-Semiring :
    (x y : type-Π-Semiring)  add-Π-Semiring x y  add-Π-Semiring y x
  commutative-add-Π-Semiring =
    commutative-mul-Commutative-Monoid additive-commutative-monoid-Π-Semiring

  mul-Π-Semiring : type-Π-Semiring  type-Π-Semiring  type-Π-Semiring
  mul-Π-Semiring = mul-Monoid multiplicative-monoid-Π-Semiring

  one-Π-Semiring : type-Π-Semiring
  one-Π-Semiring = unit-Monoid multiplicative-monoid-Π-Semiring

  associative-mul-Π-Semiring :
    (x y z : type-Π-Semiring) 
    mul-Π-Semiring (mul-Π-Semiring x y) z 
    mul-Π-Semiring x (mul-Π-Semiring y z)
  associative-mul-Π-Semiring =
    associative-mul-Monoid multiplicative-monoid-Π-Semiring

  left-unit-law-mul-Π-Semiring :
    (x : type-Π-Semiring)  mul-Π-Semiring one-Π-Semiring x  x
  left-unit-law-mul-Π-Semiring =
    left-unit-law-mul-Monoid multiplicative-monoid-Π-Semiring

  right-unit-law-mul-Π-Semiring :
    (x : type-Π-Semiring)  mul-Π-Semiring x one-Π-Semiring  x
  right-unit-law-mul-Π-Semiring =
    right-unit-law-mul-Monoid multiplicative-monoid-Π-Semiring

  left-distributive-mul-add-Π-Semiring :
    (f g h : type-Π-Semiring) 
    mul-Π-Semiring f (add-Π-Semiring g h) 
    add-Π-Semiring (mul-Π-Semiring f g) (mul-Π-Semiring f h)
  left-distributive-mul-add-Π-Semiring f g h =
    eq-htpy  i  left-distributive-mul-add-Semiring (R i) (f i) (g i) (h i))

  right-distributive-mul-add-Π-Semiring :
    (f g h : type-Π-Semiring) 
    mul-Π-Semiring (add-Π-Semiring f g) h 
    add-Π-Semiring (mul-Π-Semiring f h) (mul-Π-Semiring g h)
  right-distributive-mul-add-Π-Semiring f g h =
    eq-htpy  i  right-distributive-mul-add-Semiring (R i) (f i) (g i) (h i))

  left-zero-law-mul-Π-Semiring :
    (f : type-Π-Semiring) 
    mul-Π-Semiring zero-Π-Semiring f  zero-Π-Semiring
  left-zero-law-mul-Π-Semiring f =
    eq-htpy  i  left-zero-law-mul-Semiring (R i) (f i))

  right-zero-law-mul-Π-Semiring :
    (f : type-Π-Semiring) 
    mul-Π-Semiring f zero-Π-Semiring  zero-Π-Semiring
  right-zero-law-mul-Π-Semiring f =
    eq-htpy  i  right-zero-law-mul-Semiring (R i) (f i))

  Π-Semiring : Semiring (l1  l2)
  pr1 Π-Semiring = additive-commutative-monoid-Π-Semiring
  pr1 (pr1 (pr1 (pr2 Π-Semiring))) = mul-Π-Semiring
  pr2 (pr1 (pr1 (pr2 Π-Semiring))) = associative-mul-Π-Semiring
  pr1 (pr1 (pr2 (pr1 (pr2 Π-Semiring)))) = one-Π-Semiring
  pr1 (pr2 (pr1 (pr2 (pr1 (pr2 Π-Semiring))))) = left-unit-law-mul-Π-Semiring
  pr2 (pr2 (pr1 (pr2 (pr1 (pr2 Π-Semiring))))) = right-unit-law-mul-Π-Semiring
  pr1 (pr2 (pr2 (pr1 (pr2 Π-Semiring)))) = left-distributive-mul-add-Π-Semiring
  pr2 (pr2 (pr2 (pr1 (pr2 Π-Semiring)))) = right-distributive-mul-add-Π-Semiring
  pr1 (pr2 (pr2 Π-Semiring)) = left-zero-law-mul-Π-Semiring
  pr2 (pr2 (pr2 Π-Semiring)) = right-zero-law-mul-Π-Semiring

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