@@ -30,16 +30,18 @@ namespace CommSq
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section
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variable {A B : C} {X Y : D} {i : A ⟶ B} {p : X ⟶ Y} {u : G.obj A ⟶ X} {v : G.obj B ⟶ Y}
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- (sq : CommSq u (G.map i) p v) (adj : G ⊣ F)
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/-- When we have an adjunction `G ⊣ F`, any commutative square where the left
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map is of the form `G.map i` and the right map is `p` has an "adjoint" commutative
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square whose left map is `i` and whose right map is `F.map p`. -/
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- theorem right_adjoint : CommSq (adj.homEquiv _ _ u) i (F.map p) (adj.homEquiv _ _ v) :=
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+ theorem right_adjoint (sq : CommSq u (G.map i) p v) (adj : G ⊣ F) :
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+ CommSq (adj.homEquiv _ _ u) i (F.map p) (adj.homEquiv _ _ v) :=
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⟨by
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simp only [Adjunction.homEquiv_unit, assoc, ← F.map_comp, sq.w]
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rw [F.map_comp, Adjunction.unit_naturality_assoc]⟩
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+ variable (sq : CommSq u (G.map i) p v) (adj : G ⊣ F)
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+
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/-- The liftings of a commutative are in bijection with the liftings of its (right)
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adjoint square. -/
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def rightAdjointLiftStructEquiv : sq.LiftStruct ≃ (sq.right_adjoint adj).LiftStruct where
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section
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variable {A B : C} {X Y : D} {i : A ⟶ B} {p : X ⟶ Y} {u : A ⟶ F.obj X} {v : B ⟶ F.obj Y}
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- (sq : CommSq u i (F.map p) v) (adj : G ⊣ F)
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/-- When we have an adjunction `G ⊣ F`, any commutative square where the left
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map is of the form `i` and the right map is `F.map p` has an "adjoint" commutative
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square whose left map is `G.map i` and whose right map is `p`. -/
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- theorem left_adjoint : CommSq ((adj.homEquiv _ _).symm u) (G.map i) p ((adj.homEquiv _ _).symm v) :=
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+ theorem left_adjoint (sq : CommSq u i (F.map p) v) (adj : G ⊣ F) :
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+ CommSq ((adj.homEquiv _ _).symm u) (G.map i) p ((adj.homEquiv _ _).symm v) :=
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⟨by
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simp only [Adjunction.homEquiv_counit, assoc, ← G.map_comp_assoc, ← sq.w]
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rw [G.map_comp, assoc, Adjunction.counit_naturality]⟩
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+ variable (sq : CommSq u i (F.map p) v) (adj : G ⊣ F)
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+
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/-- The liftings of a commutative are in bijection with the liftings of its (left)
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adjoint square. -/
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- def leftAdjointLiftStructEquiv : sq.LiftStruct ≃ (sq.left_adjoint adj).LiftStruct where
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+ def leftAdjointLiftStructEquiv :
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+ sq.LiftStruct ≃ (sq.left_adjoint adj).LiftStruct where
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toFun l :=
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{ l := (adj.homEquiv _ _).symm l.l
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fac_left := by rw [← adj.homEquiv_naturality_left_symm, l.fac_left]
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