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minor style tweaks
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Signed-off-by: Ali Caglayan <[email protected]>
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Alizter committed Feb 18, 2025
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11 changes: 6 additions & 5 deletions theories/Constant.v
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Expand Up @@ -183,9 +183,9 @@ Defined.

(** We can use the above to give a funext-free approach to defining a map by factoring through a surjection. *)

Section surjective_factor.
Context {A B C} `{IsHSet C} `(f : A -> C) `(g : A -> B).
Context (resp : forall x y, g x = g y -> f x = f y).
Section SurjectiveFactor.
Context {A B C : Type} `{IsHSet C} (f : A -> C) (g : A -> B)
(resp : forall x y, g x = g y -> f x = f y).

(** The assumption [resp] tells us that [f o pr1] is weakly constant on each fiber of [g], so it factors through the propositional truncation. *)
Definition surjective_factor_aux (b : B) : merely (hfiber g b) -> C.
Expand All @@ -203,12 +203,13 @@ Section surjective_factor.
rapply center.
Defined.

Definition surjective_factor_pr {Esurj : IsSurjection g} : surjective_factor o g == f.
Definition surjective_factor_pr {Esurj : IsSurjection g}
: surjective_factor o g == f.
Proof.
intros a.
unfold surjective_factor.
nrapply (ap (y:=tr (a; idpath)) (surjective_factor_aux (g a))).
1: apply path_ishprop.
Defined.

End surjective_factor.
End SurjectiveFactor.

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