mathlib documentation


Free rings

The theory of the free ring over a type.

Main definitions

Implementation details

free_ring α is implemented as the free abelian group over the free monoid on α.


free ring

def free_ring  :
Type uType u

The free ring over a type α.

def free_ring.ring (α : Type u) :

def free_ring.inhabited (α : Type u) :

def free_ring.of {α : Type u} :
α → free_ring α

The canonical map from α to free_ring α.

theorem free_ring.induction_on {α : Type u} {C : free_ring α → Prop} (z : free_ring α) :
C (-1)(∀ (b : α), C (free_ring.of b))(∀ (x y : free_ring α), C xC yC (x + y))(∀ (x y : free_ring α), C xC yC (x * y))C z

def free_ring.lift {α : Type u} {R : Type v} [ring R] :
(α → R)free_ring α →+* R

The ring homomorphism free_ring α →+* R induced from a map α → R.

theorem free_ring.lift_of {α : Type u} {R : Type v} [ring R] (f : α → R) (x : α) :

theorem free_ring.lift_comp_of {α : Type u} {R : Type v} [ring R] (f : free_ring α →+* R) :

def {α : Type u} {β : Type v} :
(α → β)free_ring α →+* free_ring β

The canonical ring homomorphism free_ring α →+* free_ring β generated by a map α → β.

theorem free_ring.map_of {α : Type u} {β : Type v} (f : α → β) (x : α) :