-- Mathlib/Algebra/Algebra/Unitization.lean
/-- `starMap` is functorial: `starMap (ψ.comp φ) = (starMap ψ).comp (starMap φ)`. -/
lemma starMap_comp {φ : A →⋆ₙₐ[R] B} {ψ : B →⋆ₙₐ[R] C} :
    starMap (ψ.comp φ) = (starMap ψ).comp (starMap φ)

Proof state:
case h.h.h1
R : Type u_1
A : Type u_2
B : Type u_3
C : Type u_4
inst✝¹⁸ : CommSemiring R
inst✝¹⁷ : StarRing R
inst✝¹⁶ : NonUnitalSemiring A
inst✝¹⁵ : StarRing A
inst✝¹⁴ : Module R A
inst✝¹³ : SMulCommClass R A A
inst✝¹² : IsScalarTower R A A
inst✝¹¹ : NonUnitalSemiring B
inst✝¹⁰ : StarRing B
inst✝⁹ : Module R B
inst✝⁸ : SMulCommClass R B B
inst✝⁷ : IsScalarTower R B B
inst✝⁶ : NonUnitalSemiring C
inst✝⁵ : StarRing C
inst✝⁴ : Module R C
inst✝³ : SMulCommClass R C C
inst✝² : IsScalarTower R C C
inst✝¹ : StarModule R B
inst✝ : StarModule R C
φ : A →⋆ₙₐ[R] B
ψ : B →⋆ₙₐ[R] C
x✝ : A
⊢ (((↑(starMap (ψ.comp φ))).comp (inrNonUnitalStarAlgHom R A)) x✝).fst =
    (((↑((starMap ψ).comp (starMap φ))).comp (inrNonUnitalStarAlgHom R A)) x✝).fst

case h.h.h2
R : Type u_1
A : Type u_2
B : Type u_3
C : Type u_4
inst✝¹⁸ : CommSemiring R
inst✝¹⁷ : StarRing R
inst✝¹⁶ : NonUnitalSemiring A
inst✝¹⁵ : StarRing A
inst✝¹⁴ : Module R A
inst✝¹³ : SMulCommClass R A A
inst✝¹² : IsScalarTower R A A
inst✝¹¹ : NonUnitalSemiring B
inst✝¹⁰ : StarRing B
inst✝⁹ : Module R B
inst✝⁸ : SMulCommClass R B B
inst✝⁷ : IsScalarTower R B B
inst✝⁶ : NonUnitalSemiring C
inst✝⁵ : StarRing C
inst✝⁴ : Module R C
inst✝³ : SMulCommClass R C C
inst✝² : IsScalarTower R C C
inst✝¹ : StarModule R B
inst✝ : StarModule R C
φ : A →⋆ₙₐ[R] B
ψ : B →⋆ₙₐ[R] C
x✝ : A
⊢ (((↑(starMap (ψ.comp φ))).comp (inrNonUnitalStarAlgHom R A)) x✝).snd =
    (((↑((starMap ψ).comp (starMap φ))).comp (inrNonUnitalStarAlgHom R A)) x✝).snd

Tactic:
all_goals simp

Result:
no goals

Proof state:
R : Type u_1
A : Type u_2
B : Type u_3
C : Type u_4
inst✝¹⁸ : CommSemiring R
inst✝¹⁷ : StarRing R
inst✝¹⁶ : NonUnitalSemiring A
inst✝¹⁵ : StarRing A
inst✝¹⁴ : Module R A
inst✝¹³ : SMulCommClass R A A
inst✝¹² : IsScalarTower R A A
inst✝¹¹ : NonUnitalSemiring B
inst✝¹⁰ : StarRing B
inst✝⁹ : Module R B
inst✝⁸ : SMulCommClass R B B
inst✝⁷ : IsScalarTower R B B
inst✝⁶ : NonUnitalSemiring C
inst✝⁵ : StarRing C
inst✝⁴ : Module R C
inst✝³ : SMulCommClass R C C
inst✝² : IsScalarTower R C C
inst✝¹ : StarModule R B
inst✝ : StarModule R C
φ : A →⋆ₙₐ[R] B
ψ : B →⋆ₙₐ[R] C
⊢ starMap (ψ.comp φ) = (starMap ψ).comp (starMap φ)

Tactic:
ext

Result:
case h.h.h1
R : Type u_1
A : Type u_2
B : Type u_3
C : Type u_4
inst✝¹⁸ : CommSemiring R
inst✝¹⁷ : StarRing R
inst✝¹⁶ : NonUnitalSemiring A
inst✝¹⁵ : StarRing A
inst✝¹⁴ : Module R A
inst✝¹³ : SMulCommClass R A A
inst✝¹² : IsScalarTower R A A
inst✝¹¹ : NonUnitalSemiring B
inst✝¹⁰ : StarRing B
inst✝⁹ : Module R B
inst✝⁸ : SMulCommClass R B B
inst✝⁷ : IsScalarTower R B B
inst✝⁶ : NonUnitalSemiring C
inst✝⁵ : StarRing C
inst✝⁴ : Module R C
inst✝³ : SMulCommClass R C C
inst✝² : IsScalarTower R C C
inst✝¹ : StarModule R B
inst✝ : StarModule R C
φ : A →⋆ₙₐ[R] B
ψ : B →⋆ₙₐ[R] C
x✝ : A
⊢ (((↑(starMap (ψ.comp φ))).comp (inrNonUnitalStarAlgHom R A)) x✝).fst =
    (((↑((starMap ψ).comp (starMap φ))).comp (inrNonUnitalStarAlgHom R A)) x✝).fst

case h.h.h2
R : Type u_1
A : Type u_2
B : Type u_3
C : Type u_4
inst✝¹⁸ : CommSemiring R
inst✝¹⁷ : StarRing R
inst✝¹⁶ : NonUnitalSemiring A
inst✝¹⁵ : StarRing A
inst✝¹⁴ : Module R A
inst✝¹³ : SMulCommClass R A A
inst✝¹² : IsScalarTower R A A
inst✝¹¹ : NonUnitalSemiring B
inst✝¹⁰ : StarRing B
inst✝⁹ : Module R B
inst✝⁸ : SMulCommClass R B B
inst✝⁷ : IsScalarTower R B B
inst✝⁶ : NonUnitalSemiring C
inst✝⁵ : StarRing C
inst✝⁴ : Module R C
inst✝³ : SMulCommClass R C C
inst✝² : IsScalarTower R C C
inst✝¹ : StarModule R B
inst✝ : StarModule R C
φ : A →⋆ₙₐ[R] B
ψ : B →⋆ₙₐ[R] C
x✝ : A
⊢ (((↑(starMap (ψ.comp φ))).comp (inrNonUnitalStarAlgHom R A)) x✝).snd =
    (((↑((starMap ψ).comp (starMap φ))).comp (inrNonUnitalStarAlgHom R A)) x✝).snd

Proof state:
case h.h.h2
R : Type u_1
A : Type u_2
B : Type u_3
C : Type u_4
inst✝¹⁸ : CommSemiring R
inst✝¹⁷ : StarRing R
inst✝¹⁶ : NonUnitalSemiring A
inst✝¹⁵ : StarRing A
inst✝¹⁴ : Module R A
inst✝¹³ : SMulCommClass R A A
inst✝¹² : IsScalarTower R A A
inst✝¹¹ : NonUnitalSemiring B
inst✝¹⁰ : StarRing B
inst✝⁹ : Module R B
inst✝⁸ : SMulCommClass R B B
inst✝⁷ : IsScalarTower R B B
inst✝⁶ : NonUnitalSemiring C
inst✝⁵ : StarRing C
inst✝⁴ : Module R C
inst✝³ : SMulCommClass R C C
inst✝² : IsScalarTower R C C
inst✝¹ : StarModule R B
inst✝ : StarModule R C
φ : A →⋆ₙₐ[R] B
ψ : B →⋆ₙₐ[R] C
x✝ : A
⊢ (((↑(starMap (ψ.comp φ))).comp (inrNonUnitalStarAlgHom R A)) x✝).snd =
    (((↑((starMap ψ).comp (starMap φ))).comp (inrNonUnitalStarAlgHom R A)) x✝).snd

Tactic:
simp

Result:
no goals