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ecompose_e1 {A B} (e : A <~> B) : e oE 1 = e.
Proof. apply path_equiv; reflexivity. Defined.
Lemma
ecompose_e1
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv" ]
The identity equivalence is a right unit.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ecompose_1e {A B} (e : A <~> B) : 1 oE e = e.
Proof. apply path_equiv; reflexivity. Defined.
Lemma
ecompose_1e
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv" ]
The identity is a left unit.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ecompose_e_ee {A B C D} (e : A <~> B) (f : B <~> C) (g : C <~> D) : g oE (f oE e) = (g oE f) oE e.
Proof. apply path_equiv; reflexivity. Defined.
Definition
ecompose_e_ee
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv" ]
Composition is associative.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ecompose_ee_e {A B C D} (e : A <~> B) (f : B <~> C) (g : C <~> D) : (g oE f) oE e = g oE (f oE e).
Proof. apply path_equiv; reflexivity. Defined.
Definition
ecompose_ee_e
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ecompose_eV {A B} (e : A <~> B) : e oE e^-1 = 1.
Proof. apply path_equiv; apply path_forall; intro; apply eisretr. Defined.
Lemma
ecompose_eV
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv", "path_forall" ]
The left inverse law.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ecompose_Ve {A B} (e : A <~> B) : e^-1 oE e = 1.
Proof. apply path_equiv; apply path_forall; intro; apply eissect. Defined.
Lemma
ecompose_Ve
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv", "path_forall" ]
The right inverse law.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ecompose_V_ee {A B C} (e : A <~> B) (f : B <~> C) : f^-1 oE (f oE e) = e.
Proof. apply path_equiv; apply path_forall; intro; simpl; apply eissect. Defined.
Definition
ecompose_V_ee
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv", "path_forall" ]
Several auxiliary theorems about canceling inverses across associativity. These are somewhat redundant, following from earlier theorems.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ecompose_e_Ve {A B C} (e : A <~> B) (f : C <~> B) : e oE (e^-1 oE f) = f.
Proof. apply path_equiv; apply path_forall; intro; simpl; apply eisretr. Defined.
Definition
ecompose_e_Ve
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv", "path_forall" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ecompose_ee_V {A B C} (e : A <~> B) (f : B <~> C) : (f oE e) oE e^-1 = f.
Proof. apply path_equiv; apply path_forall; intro; simpl; apply ap; apply eisretr. Defined.
Definition
ecompose_ee_V
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "path_equiv", "path_forall" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ecompose_eV_e {A B C} (e : B <~> A) (f : B <~> C) : (f oE e^-1) oE e = f.
Proof. apply path_equiv; apply path_forall; intro; simpl; apply ap; apply eissect. Defined.
Definition
ecompose_eV_e
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "path_equiv", "path_forall" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
einv_ee {A B C} (e : A <~> B) (f : B <~> C) : (f oE e)^-1 = e^-1 oE f^-1.
Proof. apply path_equiv; reflexivity. Defined.
Definition
einv_ee
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv" ]
Inverse distributes over composition
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
einv_Ve {A B C} (e : A <~> C) (f : B <~> C) : (f^-1 oE e)^-1 = e^-1 oE f.
Proof. apply path_equiv; reflexivity. Defined.
Definition
einv_Ve
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
einv_eV {A B C} (e : C <~> A) (f : C <~> B) : (f oE e^-1)^-1 = e oE f^-1.
Proof. apply path_equiv; reflexivity. Defined.
Definition
einv_eV
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
einv_VV {A B C} (e : A <~> B) (f : B <~> C) : (e^-1 oE f^-1)^-1 = f oE e.
Proof. apply path_equiv; reflexivity. Defined.
Definition
einv_VV
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
einv_V {A B} (e : A <~> B) : (e^-1)^-1 = e.
Proof. apply path_equiv; reflexivity. Defined.
Definition
einv_V
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "path_equiv" ]
Inverse is an involution.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveR_Me {A B C} (e : B <~> A) (f : B <~> C) (g : A <~> C) : e = g^-1 oE f -> g oE e = f.
Proof. intro h. exact (ap (fun e => g oE e) h @ ecompose_e_Ve _ _). Defined.
Definition
emoveR_Me
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_e_Ve" ]
*** Theorems for moving things around in equations.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveR_eM {A B C} (e : B <~> A) (f : B <~> C) (g : A <~> C) : g = f oE e^-1 -> g oE e = f.
Proof. intro h. exact (ap (fun g => g oE e) h @ ecompose_eV_e _ _). Defined.
Definition
emoveR_eM
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_eV_e" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveR_Ve {A B C} (e : B <~> A) (f : B <~> C) (g : C <~> A) : e = g oE f -> g^-1 oE e = f.
Proof. intro h. exact (ap (fun e => g^-1 oE e) h @ ecompose_V_ee _ _). Defined.
Definition
emoveR_Ve
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_V_ee" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveR_eV {A B C} (e : A <~> B) (f : B <~> C) (g : A <~> C) : g = f oE e -> g oE e^-1 = f.
Proof. intro h. exact (ap (fun g => g oE e^-1) h @ ecompose_ee_V _ _). Defined.
Definition
emoveR_eV
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_ee_V" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveL_Me {A B C} (e : A <~> B) (f : A <~> C) (g : B <~> C) : g^-1 oE f = e -> f = g oE e.
Proof. intro h. exact ((ecompose_e_Ve _ _)^ @ ap (fun e => g oE e) h). Defined.
Definition
emoveL_Me
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_e_Ve" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveL_eM {A B C} (e : A <~> B) (f : A <~> C) (g : B <~> C) : f oE e^-1 = g -> f = g oE e.
Proof. intro h. exact ((ecompose_eV_e _ _)^ @ ap (fun g => g oE e) h). Defined.
Definition
emoveL_eM
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_eV_e" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveL_Ve {A B C} (e : A <~> C) (f : A <~> B) (g : B <~> C) : g oE f = e -> f = g^-1 oE e.
Proof. intro h. exact ((ecompose_V_ee _ _)^ @ ap (fun e => g^-1 oE e) h). Defined.
Definition
emoveL_Ve
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_V_ee" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveL_eV {A B C} (e : A <~> B) (f : B <~> C) (g : A <~> C) : f oE e = g -> f = g oE e^-1.
Proof. intro h. exact ((ecompose_ee_V _ _)^ @ ap (fun g => g oE e^-1) h). Defined.
Definition
emoveL_eV
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_ee_V" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveL_1M {A B} (e f : A <~> B) : e oE f^-1 = 1 -> e = f.
Proof. intro h. exact ((ecompose_eV_e _ _)^ @ ap (fun ef => ef oE f) h @ ecompose_1e _). Defined.
Definition
emoveL_1M
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_1e", "ecompose_eV_e" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveL_M1 {A B} (e f : A <~> B) : f^-1 oE e = 1 -> e = f.
Proof. intro h. exact ((ecompose_e_Ve _ _)^ @ ap (fun fe => f oE fe) h @ ecompose_e1 _). Defined.
Definition
emoveL_M1
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_e1", "ecompose_e_Ve" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveL_1V {A B} (e : A <~> B) (f : B <~> A) : e oE f = 1 -> e = f^-1.
Proof. intro h. exact ((ecompose_ee_V _ _)^ @ ap (fun ef => ef oE f^-1) h @ ecompose_1e _). Defined.
Definition
emoveL_1V
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_1e", "ecompose_ee_V" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveL_V1 {A B} (e : A <~> B) (f : B <~> A) : f oE e = 1 -> e = f^-1.
Proof. intro h. exact ((ecompose_V_ee _ _)^ @ ap (fun fe => f^-1 oE fe) h @ ecompose_e1 _). Defined.
Definition
emoveL_V1
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_V_ee", "ecompose_e1" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveR_M1 {A B} (e f : A <~> B) : 1 = e^-1 oE f -> e = f.
Proof. intro h. exact ((ecompose_e1 _)^ @ ap (fun ef => e oE ef) h @ ecompose_e_Ve _ _). Defined.
Definition
emoveR_M1
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_e1", "ecompose_e_Ve" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveR_1M {A B} (e f : A <~> B) : 1 = f oE e^-1 -> e = f.
Proof. intro h. exact ((ecompose_1e _)^ @ ap (fun fe => fe oE e) h @ ecompose_eV_e _ _). Defined.
Definition
emoveR_1M
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_1e", "ecompose_eV_e" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveR_1V {A B} (e : A <~> B) (f : B <~> A) : 1 = f oE e -> e^-1 = f.
Proof. intro h. exact ((ecompose_1e _)^ @ ap (fun fe => fe oE e^-1) h @ ecompose_ee_V _ _). Defined.
Definition
emoveR_1V
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_1e", "ecompose_ee_V" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
emoveR_V1 {A B} (e : A <~> B) (f : B <~> A) : 1 = e oE f -> e^-1 = f.
Proof. intro h. exact ((ecompose_e1 _)^ @ ap (fun ef => e^-1 oE ef) h @ ecompose_V_ee _ _). Defined.
Definition
emoveR_V1
Root
theories/EquivGroupoids.v
[ "Basics.Overture", "Basics.Equivalences", "Types.Equiv" ]
[ "ap", "ecompose_V_ee", "ecompose_e1" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ExcludedMiddle : Type0.
Axiom
ExcludedMiddle
Root
theories/ExcludedMiddle.v
[ "HoTT.Basics", "HoTT.Types" ]
[ "Type0" ]
* The law of excluded middle
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
is_global_axiom_excludedmiddle : IsGlobalAxiom ExcludedMiddle
:= {}.
Instance
is_global_axiom_excludedmiddle
Root
theories/ExcludedMiddle.v
[ "HoTT.Basics", "HoTT.Types" ]
[ "ExcludedMiddle", "IsGlobalAxiom" ]
Mark this axiom as a "global axiom", which some of our tactics will automatically handle.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
LEM : forall `{ExcludedMiddle} (P : Type), IsHProp P -> P + ~P.
Axiom
LEM
Root
theories/ExcludedMiddle.v
[ "HoTT.Basics", "HoTT.Types" ]
[ "ExcludedMiddle", "IsHProp" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ExcludedMiddle_type
:= forall (P : Type), IsHProp P -> P + ~P.
Definition
ExcludedMiddle_type
Root
theories/ExcludedMiddle.v
[ "HoTT.Basics", "HoTT.Types" ]
[ "IsHProp" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
decidable_lem `{ExcludedMiddle} (P : Type) `{IsHProp P} : Decidable P
:= LEM P _.
Instance
decidable_lem
Root
theories/ExcludedMiddle.v
[ "HoTT.Basics", "HoTT.Types" ]
[ "Decidable", "ExcludedMiddle", "IsHProp", "LEM" ]
** LEM means that all propositions are decidable
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
DNE_type
:= forall P, IsHProp P -> ~~P -> P.
Definition
DNE_type
Root
theories/ExcludedMiddle.v
[ "HoTT.Basics", "HoTT.Types" ]
[ "IsHProp" ]
** Double-negation elimination
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
LEM_to_DNE : ExcludedMiddle -> DNE_type.
Proof. intros lem P hp nnp. case (LEM P _). - auto. - intros np; elim (nnp np). Defined.
Definition
LEM_to_DNE
Root
theories/ExcludedMiddle.v
[ "HoTT.Basics", "HoTT.Types" ]
[ "DNE_type", "ExcludedMiddle", "LEM", "case" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
DNE_to_LEM `{Funext} : DNE_type -> ExcludedMiddle_type.
Proof. intros dn P hp. refine (dn (P + ~P) _ _). - apply ishprop_sum. + exact _. + exact _. + intros p np; exact (np p). - intros nlem. apply nlem. apply inr. intros p. apply nlem. apply inl. exact p. Defined.
Definition
DNE_to_LEM
Root
theories/ExcludedMiddle.v
[ "HoTT.Basics", "HoTT.Types" ]
[ "DNE_type", "ExcludedMiddle_type", "Funext", "inl", "inr", "ishprop_sum" ]
This direction requires Funext.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
allneg_from_DNE (H : DNE_type) (P : Type) `{IsHProp P} : {Q : Type & P <-> ~Q}.
Proof. exists (~P); split. - intros p np; exact (np p). - apply H; exact _. Defined.
Definition
allneg_from_DNE
Root
theories/ExcludedMiddle.v
[ "HoTT.Basics", "HoTT.Types" ]
[ "DNE_type", "IsHProp" ]
DNE is equivalent to "every proposition is a negation".
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
DNE_from_allneg (H : forall P, IsHProp P -> {Q : Type & P <-> ~Q}) : DNE_type.
Proof. intros P ? nnp. destruct (H P _) as [Q e]. apply e. intros q. apply nnp. intros p. exact (fst e p q). Defined.
Definition
DNE_from_allneg
Root
theories/ExcludedMiddle.v
[ "HoTT.Basics", "HoTT.Types" ]
[ "DNE_type", "IsHProp", "fst" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ExtensionAlong@{a b p m} {A : Type@{a}} {B : Type@{b}} (f : A -> B) (P : B -> Type@{p}) (d : forall x:A, P (f x))
:= (* { s : forall y:B, P y & forall x:A, s (f x) = d x }. *) sig@{m m} (fun (s : forall y:B, P y) => forall x:A, s (f x) = d x).
Definition
ExtensionAlong
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "sig" ]
This elimination rule (and others) can be seen as saying that, given a fibration over the codomain and a section of it over the domain, there is some *extension* of this to a section over the whole codomain. It can also be considered as an equivalent form of an [hfiber] of precomposition-with-[f] that replaces paths b...
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
lift_extensionalong@{a1 a2 amin b1 b2 bmin p1 p2 pmin m1 m2} {A : Type@{amin}} {B : Type@{bmin}} (f : A -> B) (P : B -> Type@{pmin}) (d : forall x:A, P (f x)) : ExtensionAlong@{a1 b1 p1 m1} f P d -> ExtensionAlong@{a2 b2 p2 m2} f P d.
Proof. intros ext. (** If we just give [ext], it will collapse the universes. (Anyone stepping through this proof should do [Set Printing Universes] and look at the universes to see that they're different in [ext] and in the goal.) So we decompose [ext] into two components and give them separately. *) ass...
Definition
lift_extensionalong
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtensionAlong", "m1", "m2" ]
It's occasionally useful to be able to modify those universes. For each of the universes [a], [b], [p], we give an initial one, a final one, and a "minimum" one smaller than both and where the type actually lives.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
equiv_path_extension `{Funext} {A B : Type} {f : A -> B} {P : B -> Type} {d : forall x:A, P (f x)} (ext ext' : ExtensionAlong f P d) : (ExtensionAlong f (fun y => pr1 ext y = pr1 ext' y) (fun x => pr2 ext x @ (pr2 ext' x)^)) <~> ext = ext'.
Proof. revert ext'. srapply equiv_path_from_contr. { unfold ExtensionAlong; cbn. exists (fun y => 1%path). intros x; symmetry; apply concat_pV. } destruct ext as [g gd]; unfold ExtensionAlong; cbn. refine (contr_sigma_sigma (forall y:B, P y) (fun s => forall x:A, s (f x) = ...
Definition
equiv_path_extension
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtensionAlong", "Funext", "concat_pV", "contr_equiv'", "contr_sigma_sigma", "equiv_functor_forall_id", "equiv_functor_sigma_id", "equiv_moveR_1M", "equiv_path_from_contr", "equiv_path_inverse", "path", "pr1", "pr2" ]
We called it [lift_extensionalong], but in fact it doesn't require the new universes to be bigger than the old ones, only that they both satisfy the max condition.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
path_extension `{Funext} {A B : Type} {f : A -> B} {P : B -> Type} {d : forall x:A, P (f x)} (ext ext' : ExtensionAlong f P d) : (ExtensionAlong f (fun y => pr1 ext y = pr1 ext' y) (fun x => pr2 ext x @ (pr2 ext' x)^)) -> ext = ext'
:= equiv_path_extension ext ext'.
Definition
path_extension
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtensionAlong", "Funext", "equiv_path_extension", "pr1", "pr2" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
isequiv_path_extension `{Funext} {A B : Type} {f : A -> B} {P : B -> Type} {d : forall x:A, P (f x)} (ext ext' : ExtensionAlong f P d) : IsEquiv (path_extension ext ext') | 0
:= equiv_isequiv _.
Instance
isequiv_path_extension
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtensionAlong", "Funext", "IsEquiv", "path_extension" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ExtendableAlong@{i j k l} (n : nat) {A : Type@{i}} {B : Type@{j}} (f : A -> B) (C : B -> Type@{k}) : Type@{l}
:= match n with | 0 => Unit | S n => (forall (g : forall a, C (f a)), ExtensionAlong@{i j k l} f C g) * forall (h k : forall b, C b), ExtendableAlong n f (fun b => h b = k b) end.
Fixpoint
ExtendableAlong
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtensionAlong", "Unit", "nat" ]
Here is the iterated version.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
lift_extendablealong@{a1 a2 amin b1 b2 bmin p1 p2 pmin m1 m2} (n : nat) {A : Type@{amin}} {B : Type@{bmin}} (f : A -> B) (P : B -> Type@{pmin}) : ExtendableAlong@{a1 b1 p1 m1} n f P -> ExtendableAlong@{a2 b2 p2 m2} n f P.
Proof. revert P; simple_induction n n IH; intros P. - intros _; exact tt. - intros ext; split. + intros g; exact (lift_extensionalong@{a1 a2 amin b1 b2 bmin p1 p2 pmin m1 m2} _ _ _ (fst ext g)). + intros h k. (** Unless we give the universe explicitly here, [kmin] gets collapsed to [k1]...
Definition
lift_extendablealong
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "fst", "lift_extensionalong", "m1", "m2", "nat", "simple_induction", "snd" ]
We can modify the universes, as with [ExtensionAlong].
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
equiv_extendable_pathsplit `{Funext} (n : nat) {A B : Type} (C : B -> Type) (f : A -> B) : ExtendableAlong n f C <~> PathSplit n (fun (g : forall b, C b) => g oD f).
Proof. generalize dependent C; simple_induction n n IHn; intros C. 1:exact equiv_idmap. refine (_ *E _); simpl. - refine (equiv_functor_forall' 1 _); intros g; simpl. refine (equiv_functor_sigma' 1 _); intros rec. apply equiv_path_forall. - refine (equiv_functor_forall' 1 _); intros h. ...
Definition
equiv_extendable_pathsplit
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "Funext", "PathSplit", "equiv_apD10", "equiv_functor_forall'", "equiv_functor_pathsplit", "equiv_functor_sigma'", "equiv_idmap", "equiv_inverse", "equiv_path_forall", "nat", "simple_induction" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
isequiv_extendable `{Funext} (n : nat) {A B : Type} {C : B -> Type} {f : A -> B} : ExtendableAlong n.+2 f C -> IsEquiv (fun g => g oD f)
:= isequiv_pathsplit n o (equiv_extendable_pathsplit n.+2 C f).
Definition
isequiv_extendable
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "Funext", "IsEquiv", "equiv_extendable_pathsplit", "isequiv_pathsplit", "nat" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ishprop_extendable `{Funext} (n : nat) {A B : Type} (C : B -> Type) (f : A -> B) : IsHProp (ExtendableAlong n.+2 f C).
Proof. exact (istrunc_equiv_istrunc _ (equiv_extendable_pathsplit n.+2 C f)^-1). Defined.
Instance
ishprop_extendable
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "Funext", "IsHProp", "equiv_extendable_pathsplit", "istrunc_equiv_istrunc", "nat" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
equiv_extendable_isequiv `{Funext} (n : nat) {A B : Type} (C : B -> Type) (f : A -> B) : ExtendableAlong n.+2 f C <~> IsEquiv (fun (g : forall b, C b) => g oD f).
Proof. etransitivity. - apply equiv_extendable_pathsplit. - apply equiv_pathsplit_isequiv. Defined.
Definition
equiv_extendable_isequiv
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "Funext", "IsEquiv", "equiv_extendable_pathsplit", "equiv_pathsplit_isequiv", "nat" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extension_isequiv_precompose {A : Type} {B : Type} (f : A -> B) (C : B -> Type) : IsEquiv (fun (g : forall b, C b) => g oD f) -> forall g, ExtensionAlong f C g.
Proof. intros E g. pose (e := Build_Equiv _ _ _ E). exists (e^-1 g). apply apD10. exact (eisretr e g). Defined.
Definition
extension_isequiv_precompose
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtensionAlong", "IsEquiv", "apD10" ]
Without [Funext], we can prove a small part of the above equivalence. We suspect that the rest requires [Funext].
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_postcompose' (n : nat) {A B : Type} (C D : B -> Type) (f : A -> B) (g : forall b, C b <~> D b) : ExtendableAlong n f C -> ExtendableAlong n f D.
Proof. generalize dependent C; revert D. simple_induction n n IH; intros C D g; simpl. 1:exact idmap. refine (functor_prod _ _). - refine (functor_forall (functor_forall idmap (fun a => (g (f a))^-1)) _); intros h; simpl. refine (functor_sigma...
Definition
extendable_postcompose'
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "composeD", "equiv_ap", "equiv_inverse", "functor_arrow", "functor_forall", "functor_prod", "functor_sigma", "idmap", "moveR_equiv_M", "nat", "simple_induction" ]
Postcomposition with a known equivalence. Note that this does not require funext to define, although showing that it is an equivalence would require funext.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_postcompose (n : nat) {A B : Type} (C D : B -> Type) (f : A -> B) (g : forall b, C b -> D b) `{forall b, IsEquiv (g b)} : ExtendableAlong n f C -> ExtendableAlong n f D
:= extendable_postcompose' n C D f (fun b => Build_Equiv _ _ (g b) _).
Definition
extendable_postcompose
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "IsEquiv", "extendable_postcompose'", "nat" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_compose (n : nat) {A B C : Type} (P : C -> Type) (f : A -> B) (g : B -> C) : ExtendableAlong n g P -> ExtendableAlong n f (fun b => P (g b)) -> ExtendableAlong n (g o f) P.
Proof. revert P; simple_induction n n IHn; intros P extg extf; [ exact tt | split ]. - intros h. exists ((fst extg (fst extf h).1).1); intros a. refine ((fst extg (fst extf h).1).2 (f a) @ _). exact ((fst extf h).2 a). - intros h k. apply IHn. + exact (snd extg h k). + ex...
Definition
extendable_compose
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "fst", "nat", "simple_induction", "snd" ]
Composition of the maps we extend along. This also does not require funext.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
cancelL_extendable (n : nat) {A B C : Type} (P : C -> Type) (f : A -> B) (g : B -> C) : ExtendableAlong n g P -> ExtendableAlong n (g o f) P -> ExtendableAlong n f (fun b => P (g b)).
Proof. revert P; simple_induction n n IHn; intros P extg extgf; [ exact tt | split ]. - intros h. exists ((fst extgf h).1 oD g); intros a. exact ((fst extgf h).2 a). - intros h k. pose (h' := (fst extg h).1). pose (k' := (fst extg k).1). refine (extendable_postcompose' n (fun b...
Definition
cancelL_extendable
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "equiv_concat_lr", "extendable_postcompose'", "fst", "nat", "simple_induction", "snd" ]
And cancellation
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
cancelR_extendable (n : nat) {A B C : Type} (P : C -> Type) (f : A -> B) (g : B -> C) : ExtendableAlong n.+1 f (fun b => P (g b)) -> ExtendableAlong n (g o f) P -> ExtendableAlong n g P.
Proof. revert P; simple_induction n n IHn; intros P extf extgf; [ exact tt | split ]. - intros h. exists ((fst extgf (h oD f)).1); intros b. refine ((fst (snd extf ((fst extgf (h oD f)).1 oD g) h) _).1 b); intros a. apply ((fst extgf (h oD f)).2). - intros h k. apply IHn. + exa...
Definition
cancelR_extendable
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "fst", "nat", "simple_induction", "snd" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_homotopic (n : nat) {A B : Type} (C : B -> Type) (f : A -> B) {g : A -> B} (p : f == g) : ExtendableAlong n f C -> ExtendableAlong n g C.
Proof. revert C; simple_induction n n IHn; intros C extf; [ exact tt | split ]. - intros h. exists ((fst extf (fun a => (p a)^ # h a)).1); intros a. refine ((apD ((fst extf (fun a => (p a)^ # h a)).1) (p a))^ @ _). apply moveR_transport_p. exact ((fst extf (fun a => (p a)^ # h a)).2 a). ...
Definition
extendable_homotopic
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "apD", "fst", "moveR_transport_p", "nat", "simple_induction", "snd" ]
And transfer across homotopies
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_equiv (n : nat) {A B : Type} (C : B -> Type) (f : A -> B) `{IsEquiv _ _ f} : ExtendableAlong n f C.
Proof. revert C; simple_induction n n IHn; intros C; [ exact tt | split ]. - intros h. exists (fun b => eisretr f b # h (f^-1 b)); intros a. refine (transport2 C (eisadj f a) _ @ _). refine ((transport_compose C f _ _)^ @ _). exact (apD h (eissect f a)). - intros h k. apply IHn...
Definition
extendable_equiv
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "IsEquiv", "apD", "nat", "simple_induction", "transport2", "transport_compose" ]
We can extend along equivalences
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_contr (n : nat) {A B : Type} (C : B -> Type) (f : A -> B) `{forall b, Contr (C b)} : ExtendableAlong n f C.
Proof. generalize dependent C; simple_induction n n IHn; intros C ?; [ exact tt | split ]. - intros h. exists (fun _ => center _); intros a. apply contr. - intros h k. apply IHn; exact _. Defined.
Definition
extendable_contr
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "Contr", "ExtendableAlong", "center", "contr", "nat", "simple_induction" ]
And into contractible types
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_homotopy (n : nat) {A B : Type} (C : B -> Type) (f : A -> B) (h k : forall b, C b) : ExtendableAlong n.+1 f C -> ExtendableAlong n f (fun b => h b = k b).
Proof. revert C h k; simple_induction n n IHn; intros C h k ext; [exact tt | split]. - intros p. exact (fst (snd ext h k) p). - intros p q. apply IHn, ext. Defined.
Definition
extendable_homotopy
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "fst", "nat", "simple_induction", "snd" ]
This is inherited by types of homotopies.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooExtendableAlong@{i j k l} {A : Type@{i}} {B : Type@{j}} (f : A -> B) (C : B -> Type@{k}) : Type@{l}
:= forall n : nat, ExtendableAlong@{i j k l} n f C.
Definition
ooExtendableAlong
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "nat" ]
And the oo-version.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
lift_ooextendablealong@{a1 a2 amin b1 b2 bmin p1 p2 pmin m1 m2} {A : Type@{amin}} {B : Type@{bmin}} (f : A -> B) (P : B -> Type@{pmin}) : ooExtendableAlong@{a1 b1 p1 m1} f P -> ooExtendableAlong@{a2 b2 p2 m2} f P
:= fun ext n => lift_extendablealong@{a1 a2 amin b1 b2 bmin p1 p2 pmin m1 m2} n f P (ext n).
Definition
lift_ooextendablealong
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "lift_extendablealong", "m1", "m2", "ooExtendableAlong" ]
Universe modification.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
isequiv_ooextendable `{Funext} {A B : Type} (C : B -> Type) (f : A -> B) : ooExtendableAlong f C -> IsEquiv (fun g => g oD f)
:= fun ps => isequiv_extendable 0 (fst (ps 1%nat), snd (ps 2)).
Definition
isequiv_ooextendable
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "Funext", "IsEquiv", "fst", "isequiv_extendable", "nat", "ooExtendableAlong", "snd" ]
We take part of the data from [ps 1] and part from [ps 2] so that the inverse chosen is the expected one.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
equiv_ooextendable_pathsplit `{Funext} {A B : Type} (C : B -> Type) (f : A -> B) : ooExtendableAlong f C <~> ooPathSplit (fun (g : forall b, C b) => g oD f).
Proof. refine (equiv_functor_forall' 1 _); intros n. apply equiv_extendable_pathsplit. Defined.
Definition
equiv_ooextendable_pathsplit
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "Funext", "equiv_extendable_pathsplit", "equiv_functor_forall'", "ooExtendableAlong", "ooPathSplit" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ishprop_ooextendable `{Funext} {A B : Type} (C : B -> Type) (f : A -> B) : IsHProp (ooExtendableAlong f C).
Proof. exact (istrunc_equiv_istrunc _ (equiv_ooextendable_pathsplit C f)^-1). Defined.
Instance
ishprop_ooextendable
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "Funext", "IsHProp", "equiv_ooextendable_pathsplit", "istrunc_equiv_istrunc", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
equiv_ooextendable_isequiv `{Funext} {A B : Type} (C : B -> Type) (f : A -> B) : ooExtendableAlong f C <~> IsEquiv (fun (g : forall b, C b) => g oD f)
:= equiv_oopathsplit_isequiv _ oE equiv_ooextendable_pathsplit _ _.
Definition
equiv_ooextendable_isequiv
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "Funext", "IsEquiv", "equiv_ooextendable_pathsplit", "equiv_oopathsplit_isequiv", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_postcompose {A B : Type} (C D : B -> Type) (f : A -> B) (g : forall b, C b -> D b) `{forall b, IsEquiv (g b)} : ooExtendableAlong f C -> ooExtendableAlong f D
:= fun ppp n => extendable_postcompose n C D f g (ppp n).
Definition
ooextendable_postcompose
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "IsEquiv", "extendable_postcompose", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_postcompose' {A B : Type} (C D : B -> Type) (f : A -> B) (g : forall b, C b <~> D b) : ooExtendableAlong f C -> ooExtendableAlong f D
:= fun ppp n => extendable_postcompose' n C D f g (ppp n).
Definition
ooextendable_postcompose'
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "extendable_postcompose'", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_compose {A B C : Type} (P : C -> Type) (f : A -> B) (g : B -> C) : ooExtendableAlong g P -> ooExtendableAlong f (fun b => P (g b)) -> ooExtendableAlong (g o f) P
:= fun extg extf n => extendable_compose n P f g (extg n) (extf n).
Definition
ooextendable_compose
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "extendable_compose", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
cancelL_ooextendable {A B C : Type} (P : C -> Type) (f : A -> B) (g : B -> C) : ooExtendableAlong g P -> ooExtendableAlong (g o f) P -> ooExtendableAlong f (fun b => P (g b))
:= fun extg extgf n => cancelL_extendable n P f g (extg n) (extgf n).
Definition
cancelL_ooextendable
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "cancelL_extendable", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
cancelR_ooextendable {A B C : Type} (P : C -> Type) (f : A -> B) (g : B -> C) : ooExtendableAlong f (fun b => P (g b)) -> ooExtendableAlong (g o f) P -> ooExtendableAlong g P
:= fun extf extgf n => cancelR_extendable n P f g (extf n.+1) (extgf n).
Definition
cancelR_ooextendable
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "cancelR_extendable", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_homotopic {A B : Type} (C : B -> Type) (f : A -> B) {g : A -> B} (p : f == g) : ooExtendableAlong f C -> ooExtendableAlong g C
:= fun extf n => extendable_homotopic n C f p (extf n).
Definition
ooextendable_homotopic
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "extendable_homotopic", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_equiv {A B : Type} (C : B -> Type) (f : A -> B) `{IsEquiv _ _ f} : ooExtendableAlong f C
:= fun n => extendable_equiv n C f.
Definition
ooextendable_equiv
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "IsEquiv", "extendable_equiv", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_contr {A B : Type} (C : B -> Type) (f : A -> B) `{forall b, Contr (C b)} : ooExtendableAlong f C
:= fun n => extendable_contr n C f.
Definition
ooextendable_contr
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "Contr", "extendable_contr", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_homotopy {A B : Type} (C : B -> Type) (f : A -> B) (h k : forall b, C b) : ooExtendableAlong f C -> ooExtendableAlong f (fun b => h b = k b).
Proof. intros ext n; apply extendable_homotopy, ext. Defined.
Definition
ooextendable_homotopy
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "extendable_homotopy", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_isnull_fibers {A B} (f : A -> B) (C : B -> Type) : (forall b, ooExtendableAlong (const_tt (hfiber f b)) (fun _ => C b)) -> ooExtendableAlong f C.
Proof. intros orth n; revert C orth. induction n as [|n IHn]; intros C orth; [exact tt | split]. - intros g. exists (fun b => (fst (orth b 1%nat) (fun x => x.2 # g x.1)).1 tt). intros a. rewrite (path_unit tt (const_tt _ a)). exact ((fst (orth (f a) 1%nat) _).2 (a ; 1)). - intros...
Definition
ooextendable_isnull_fibers
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "const_tt", "fst", "hfiber", "induction", "nat", "ooExtendableAlong", "ooextendable_homotopy", "path_unit" ]
Extendability of a family [C] along a map [f] can be detected by extendability of the constant family [C b] along the projection from the corresponding fiber of [f] to [Unit]. Note that this is *not* an if-and-only-if; the hypothesis can be genuinely stronger than the conclusion.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
cyl_extension {A B} (f : A -> B) (C : Cyl f -> Type) (g : forall a, C (cyl a)) (ext : ExtensionAlong cyl C g) : ExtensionAlong cyl C g.
Proof. srefine (Cyl_ind C g (ext.1 o cyr) _ ; _); intros a. + refine ((ext.2 a)^ @Dl _)%dpath. apply apD. + reflexivity. (** The point is that this equality is now definitional. *) Defined.
Definition
cyl_extension
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "Cyl", "Cyl_ind", "ExtensionAlong", "apD", "cyl", "cyr" ]
If a family is extendable along a cofibration (i.e. a mapping cylinder), it is extendable definitionally.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
cyl_extendable (n : nat) {A B} (f : A -> B) (C : Cyl f -> Type) (ext : ExtendableAlong n cyl C) : ExtendableAlong n cyl C.
Proof. revert C ext; simple_induction n n IH; intros C ext; [ exact tt | split ]. - intros g. apply cyl_extension. exact (fst ext g). - intros h k; apply IH. exact (snd ext h k). Defined.
Definition
cyl_extendable
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "Cyl", "ExtendableAlong", "cyl", "cyl_extension", "fst", "nat", "simple_induction", "snd" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
cyl_ooextendable {A B} (f : A -> B) (C : Cyl f -> Type) (ext : ooExtendableAlong cyl C) : ooExtendableAlong cyl C
:= fun n => cyl_extendable n f C (ext n).
Definition
cyl_ooextendable
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "Cyl", "cyl", "cyl_extendable", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
cyl_extension' {A B} (f : A -> B) (C : B -> Type) (g : forall a, C (pr_cyl (cyl a))) (ext : ExtensionAlong f C g) : ExtensionAlong cyl (C o pr_cyl) g.
Proof. rapply cyl_extension. exists (ext.1 o pr_cyl). intros x; apply ext.2. Defined.
Definition
cyl_extension'
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtensionAlong", "cyl", "cyl_extension", "pr_cyl" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
cyl_extendable' (n : nat) {A B} (f : A -> B) (C : B -> Type) (ext : ExtendableAlong n f C) : ExtendableAlong n cyl (C o (pr_cyl' f)).
Proof. rapply cyl_extendable. refine (cancelL_extendable n C cyl pr_cyl _ ext). rapply extendable_equiv. Defined.
Definition
cyl_extendable'
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "cancelL_extendable", "cyl", "cyl_extendable", "extendable_equiv", "nat", "pr_cyl", "pr_cyl'" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
cyl_ooextendable' {A B} (f : A -> B) (C : B -> Type) (ext : ooExtendableAlong f C) : ooExtendableAlong cyl (C o (pr_cyl' f))
:= fun n => cyl_extendable' n f C (ext n).
Definition
cyl_ooextendable'
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "cyl", "cyl_extendable'", "ooExtendableAlong", "pr_cyl'" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extension_functor_prod {A B A' B'} (f : A -> A') (g : B -> B') (P : A' * B' -> Type) (ef : forall b', ExtendableAlong 1 f (fun a' => P (a',b'))) (eg : forall a', ExtendableAlong 1 g (fun b' => P (a',b'))) (s : forall z, P (functor_prod f g z)) : ExtensionAlong (f...
Proof. srefine (_;_). - intros [a' b']; revert b'. refine ((fst (eg a') _).1). intros b; revert a'. refine ((fst (ef (g b)) _).1). intros a. exact (s (a,b)). - intros [a b]; cbn. refine ((fst (eg (f a)) _).2 b @ _). exact ((fst (ef (g b)) _).2 a). Defined.
Definition
extension_functor_prod
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "A'", "B'", "ExtendableAlong", "ExtensionAlong", "fst", "functor_prod" ]
** Extendability along [functor_prod]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_functor_prod (n : nat) {A B A' B'} (f : A -> A') (g : B -> B') (P : A' * B' -> Type) (ef : forall b', ExtendableAlong n f (fun a' => P (a',b'))) (eg : forall a', ExtendableAlong n g (fun b' => P (a',b'))) : ExtendableAlong n (functor_prod f g) P.
Proof. revert P ef eg; simple_induction n n IH; intros P ef eg; [ exact tt | split ]. - apply extension_functor_prod. + intros b'; exact (fst (ef b'), fun _ _ => tt). + intros a'; exact (fst (eg a'), fun _ _ => tt). - intros h k; apply IH. + intros b'; apply (snd (ef b')). + intros a'; apply (snd ...
Definition
extendable_functor_prod
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "A'", "B'", "ExtendableAlong", "extension_functor_prod", "fst", "functor_prod", "nat", "simple_induction", "snd" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_functor_prod {A B A' B'} (f : A -> A') (g : B -> B') (P : A' * B' -> Type) (ef : forall b', ooExtendableAlong f (fun a' => P (a',b'))) (eg : forall a', ooExtendableAlong g (fun b' => P (a',b'))) : ooExtendableAlong (functor_prod f g) P
:= fun n => extendable_functor_prod n f g P (fun b' => ef b' n) (fun a' => eg a' n).
Definition
ooextendable_functor_prod
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "A'", "B'", "extendable_functor_prod", "functor_prod", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extension_functor_sigma_id {A} {P Q : A -> Type} (f : forall a, P a -> Q a) (C : sig Q -> Type) (ef : forall a, ExtendableAlong 1 (f a) (fun v => C (a;v))) (s : forall z, C (functor_sigma idmap f z)) : ExtensionAlong (functor_sigma idmap f) C s.
Proof. srefine (_;_). - intros [a v]; revert v. refine ((fst (ef a) _).1). intros u. exact (s (a;u)). - intros [a u]; cbn. exact ((fst (ef a) _).2 u). Defined.
Definition
extension_functor_sigma_id
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "ExtensionAlong", "fst", "functor_sigma", "idmap", "sig" ]
** Extendability along [functor_sigma]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_functor_sigma_id n {A} {P Q : A -> Type} (f : forall a, P a -> Q a) (C : sig Q -> Type) (ef : forall a, ExtendableAlong n (f a) (fun v => C (a;v))) : ExtendableAlong n (functor_sigma idmap f) C.
Proof. revert C ef; simple_induction n n IH; intros C ef; [ exact tt | split ]. - apply extension_functor_sigma_id. intros a; exact (fst (ef a) , fun _ _ => tt). - intros h k; apply IH. intros a; apply (snd (ef a)). Defined.
Definition
extendable_functor_sigma_id
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "extension_functor_sigma_id", "fst", "functor_sigma", "idmap", "sig", "simple_induction", "snd" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_functor_sigma_id {A} {P Q : A -> Type} (f : forall a, P a -> Q a) (C : sig Q -> Type) (ef : forall a, ooExtendableAlong (f a) (fun v => C (a;v))) : ooExtendableAlong (functor_sigma idmap f) C
:= fun n => extendable_functor_sigma_id n f C (fun a => ef a n).
Definition
ooextendable_functor_sigma_id
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "extendable_functor_sigma_id", "functor_sigma", "idmap", "ooExtendableAlong", "sig" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
HomotopyExtensionAlong {A B} {Q : B -> Type} (f : A -> B) (C : sig Q -> Type) (p : forall (a:A) (v:Q (f a)), C (f a;v))
:= { q : forall (b:B) (v:Q b), C (b;v) & forall a v, q (f a) v = p a v }.
Definition
HomotopyExtensionAlong
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "sig" ]
Unfortunately, the technology of [ExtensionAlong] seems to be insufficient to state a general, funext-free version of [extension_functor_sigma] with a non-identity map on the bases; the hypothesis on the fiberwise map would have to be the existence of an extension in a function-type "up to pointwise equality". With wi...
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
HomotopyExtendableAlong (n : nat) {A B} {Q : B -> Type} (f : A -> B) (C : sig Q -> Type) : Type
:= match n with | 0 => Unit | S n => ((forall (p : forall (a:A) (v:Q (f a)), C (f a;v)), HomotopyExtensionAlong f C p) * (forall (h k : forall z, C z), HomotopyExtendableAlong n f (fun z => h z = k z))) end.
Fixpoint
HomotopyExtendableAlong
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "HomotopyExtensionAlong", "Unit", "nat", "sig" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooHomotopyExtendableAlong {A B} {Q : B -> Type} (f : A -> B) (C : sig Q -> Type)
:= forall n, HomotopyExtendableAlong n f C.
Definition
ooHomotopyExtendableAlong
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "HomotopyExtendableAlong", "sig" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extension_functor_sigma {A B} {P : A -> Type} {Q : B -> Type} (f : A -> B) (g : forall a, P a -> Q (f a)) (C : sig Q -> Type) (ef : HomotopyExtendableAlong 1 f C) (eg : forall a, ExtendableAlong 1 (g a) (fun v => C (f a ; v))) (s : forall z, C (functor_s...
Proof. srefine (_;_). - intros [b v]; revert b v. refine ((fst ef _).1). intros a. refine ((fst (eg a) _).1). intros u. exact (s (a;u)). - intros [a u]; cbn. refine ((fst ef _).2 _ _ @ _). exact ((fst (eg a) _).2 u). Defined.
Definition
extension_functor_sigma
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "ExtensionAlong", "HomotopyExtendableAlong", "fst", "functor_sigma", "sig" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_functor_sigma (n : nat) {A B} {P : A -> Type} {Q : B -> Type} (f : A -> B) (g : forall a, P a -> Q (f a)) (C : sig Q -> Type) (ef : HomotopyExtendableAlong n f C) (eg : forall a, ExtendableAlong n (g a) (fun v => C (f a ; v))) : ExtendableAlong n (func...
Proof. revert C ef eg; simple_induction n n IH; intros C ef eg; [ exact tt | split ]. - apply extension_functor_sigma. + exact (fst ef, fun _ _ => tt). + intros a; exact (fst (eg a) , fun _ _ => tt). - intros h k; apply IH. + exact (snd ef h k). + intros a; apply (snd (eg a)). Defined.
Definition
extendable_functor_sigma
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "ExtendableAlong", "HomotopyExtendableAlong", "extension_functor_sigma", "fst", "functor_sigma", "nat", "sig", "simple_induction", "snd" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_functor_sigma {A B} {P : A -> Type} {Q : B -> Type} (f : A -> B) (g : forall a, P a -> Q (f a)) (C : sig Q -> Type) (ef : ooHomotopyExtendableAlong f C) (eg : forall a, ooExtendableAlong (g a) (fun v => C (f a ; v))) : ooExtendableAlong (functor_sigm...
:= fun n => extendable_functor_sigma n f g C (ef n) (fun a => eg a n).
Definition
ooextendable_functor_sigma
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "extendable_functor_sigma", "functor_sigma", "ooExtendableAlong", "ooHomotopyExtendableAlong", "sig" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extension_functor_sum {A B A' B'} (f : A -> A') (g : B -> B') (P : A' + B' -> Type) (ef : ExtendableAlong 1 f (P o inl)) (eg : ExtendableAlong 1 g (P o inr)) (h : forall z, P (functor_sum f g z)) : ExtensionAlong (functor_sum f g) P h.
Proof. srefine (sum_ind _ _ _ ; sum_ind _ _ _). + exact (fst ef (h o inl)).1. + exact (fst eg (h o inr)).1. + exact (fst ef (h o inl)).2. + exact (fst eg (h o inr)).2. Defined.
Definition
extension_functor_sum
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "A'", "B'", "ExtendableAlong", "ExtensionAlong", "fst", "functor_sum", "inl", "inr", "sum_ind" ]
** Extendability along [functor_sum]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extendable_functor_sum (n : nat) {A B A' B'} (f : A -> A') (g : B -> B') (P : A' + B' -> Type) (ef : ExtendableAlong n f (P o inl)) (eg : ExtendableAlong n g (P o inr)) : ExtendableAlong n (functor_sum f g) P.
Proof. revert P ef eg; induction n as [|n IH]; intros P ef eg; [ exact tt | split ]. - intros h; apply extension_functor_sum. + exact (fst ef, fun _ _ => tt). + exact (fst eg, fun _ _ => tt). - intros h k. apply IH. + exact (snd ef (h o inl) (k o inl)). + exact (snd eg (h o inr) (k o inr)). De...
Definition
extendable_functor_sum
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "A'", "B'", "ExtendableAlong", "extension_functor_sum", "fst", "functor_sum", "induction", "inl", "inr", "nat", "snd" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
ooextendable_functor_sum {A B A' B'} (f : A -> A') (g : B -> B') (P : A' + B' -> Type) (ef : ooExtendableAlong f (P o inl)) (eg : ooExtendableAlong g (P o inr)) : ooExtendableAlong (functor_sum f g) P.
Proof. intros n; apply extendable_functor_sum; [ apply ef | apply eg ]. Defined.
Definition
ooextendable_functor_sum
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "A'", "B'", "extendable_functor_sum", "functor_sum", "inl", "inr", "ooExtendableAlong" ]
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f
extension_functor_coeq {B A f g B' A' f' g'} {h : B -> B'} {k : A -> A'} {p : k o f == f' o h} {q : k o g == g' o h} {C : Coeq f' g' -> Type} (ek : ExtendableAlong 1 k (C o coeq)) (eh : forall (u v : forall x : B', C (coeq (g' x))), ExtendableAlong 1...
Proof. (** We start by changing the problem to involve [CylCoeq] with cofibrations. *) set (C' := C o pr_cylcoeq p q). set (s' x := pr_cyl_cylcoeq p q x # s x). assert (e : ExtensionAlong (cyl_cylcoeq p q) C' s'). 2:{ pose (ex := fst (extendable_equiv 1 C (pr_cylcoeq p q)) e.1). exists (ex.1); intros x....
Definition
extension_functor_coeq
Root
theories/Extensions.v
[ "HoTT.Basics", "HoTT.Types", "Equiv.PathSplit", "Homotopy.IdentitySystems", "Cubical.DPath", "Cubical.DPathSquare", "Colimits.Coeq", "Colimits.MappingCylinder" ]
[ "A'", "B'", "Coeq", "Coeq_ind", "Coeq_ind_beta_cglue", "Cyl", "DPath", "ExtendableAlong", "ExtensionAlong", "apD", "ap_V", "ap_compose", "ap_cyl_cylcoeq_cglue", "ap_pr_cylcoeq_cglue", "cancelL_extendable", "cglue", "coeq", "cyl", "cyl_cylcoeq", "cyl_extendable", "cyl_extendab...
First we show that if we can extend in [C] along [k], and we can extend in appropriate path-types of [C] along [h], then we can extend in [C] along [functor_coeq]. This is where the hard work is.
https://github.com/HoTT/Coq-HoTT
b75eadc7cb2bc59dca415bf47662a9290f82dc5f