Morphisms of star rings #
This file defines a new type of morphism between (non-unital) rings A
and B
where both
A
and B
are equipped with a star
operation. This morphism, namely NonUnitalStarRingHom
, is
a direct extension of its non-star
red counterpart with a field map_star
which guarantees it
preserves the star operation.
As with NonUnitalRingHom
, the multiplications are not assumed to be associative or unital.
Main definitions #
Implementation #
This file is heavily inspired by Mathlib/Algebra/Star/StarAlgHom.lean
.
Tags #
non-unital, ring, morphism, star
Non-unital star ring homomorphisms #
A non-unital ⋆-ring homomorphism is a non-unital ring homomorphism between non-unital
non-associative semirings A
and B
equipped with a star
operation, and this homomorphism is
also star
-preserving.
- toFun : A → B
By definition, a non-unital ⋆-ring homomorphism preserves the
star
operation.
Instances For
α →⋆ₙ+* β
denotes the type of non-unital ring homomorphisms from α
to β
.
Equations
Instances For
NonUnitalStarRingHomClass F A B
states that F
is a type of non-unital ⋆-ring homomorphisms.
You should also extend this typeclass when you extend NonUnitalStarRingHom
.
Instances
Turn an element of a type F
satisfying NonUnitalStarRingHomClass F A B
into an actual
NonUnitalStarRingHom
. This is declared as the default coercion from F
to A →⋆ₙ+ B
.
Equations
Instances For
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See Note [custom simps projection]
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Instances For
Copy of a NonUnitalStarRingHom
with a new toFun
equal to the old one. Useful
to fix definitional equalities.
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Instances For
The identity as a non-unital ⋆-ring homomorphism.
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Instances For
The composition of non-unital ⋆-ring homomorphisms, as a non-unital ⋆-ring homomorphism.
Equations
Instances For
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Star ring equivalences #
A ⋆-ring equivalence is an equivalence preserving addition, multiplication, and the star operation, which allows for considering both unital and non-unital equivalences with a single structure.
- toFun : A → B
- invFun : B → A
- left_inv : Function.LeftInverse self.invFun self.toFun
- right_inv : Function.RightInverse self.invFun self.toFun
By definition, a ⋆-ring equivalence preserves the
star
operation.
Instances For
A ⋆-ring equivalence is an equivalence preserving addition, multiplication, and the star operation, which allows for considering both unital and non-unital equivalences with a single structure.
Equations
Instances For
StarRingEquivClass F A B
asserts F
is a type of bundled ⋆-ring equivalences between A
and
B
.
You should also extend this typeclass when you extend StarRingEquiv
.
By definition, a ⋆-ring equivalence preserves the
star
operation.
Instances
Turn an element of a type F
satisfying StarRingEquivClass F A B
into an actual
StarRingEquiv
. This is declared as the default coercion from F
to A ≃⋆+* B
.
Equations
Instances For
Any type satisfying StarRingEquivClass
can be cast into StarRingEquiv
via
StarRingEquivClass.toStarRingEquiv
.
Equations
Auxiliary definition to avoid looping in dsimp
with StarRingEquiv.symm_mk
.
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Instances For
If a (unital or non-unital) star ring morphism has an inverse, it is an isomorphism of star rings.
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Instances For
Promote a bijective star ring homomorphism to a star ring equivalence.