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chore: push-out -> cobase-change
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TOTBWF committed Feb 1, 2023
1 parent fc84619 commit cdeba29
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16 changes: 8 additions & 8 deletions src/Cat/Displayed/Bifibration.lagda.md
Original file line number Diff line number Diff line change
Expand Up @@ -81,10 +81,10 @@ module _ (bifib : is-bifibration) where
open Cat.Displayed.Cartesian.Indexing ℰ fibration
open Cat.Displayed.Cocartesian.Indexing ℰ opfibration

push-out⊣base-change
cobase-change⊣base-change
: {x y} (f : Hom x y)
push-out f ⊣ base-change f
push-out⊣base-change {x} {y} f =
cobase-change f ⊣ base-change f
cobase-change⊣base-change {x} {y} f =
hom-natural-iso→adjoints $
(opfibration→hom-iso opfibration f ni⁻¹) ni∘ fibration→hom-iso fibration f
```
Expand All @@ -108,11 +108,11 @@ module _ (fib : Cartesian-fibration) where
open Cartesian-fibration fib
open Cat.Displayed.Cartesian.Indexing ℰ fib

left-adjoint-reindexing→opfibration
left-adjoint-base-change→opfibration
: (L : {x y} (f : Hom x y) Functor (Fibre ℰ x) (Fibre ℰ y))
( {x y} (f : Hom x y) (L f ⊣ base-change f))
Cocartesian-fibration
left-adjoint-reindexing→opfibration L adj =
left-adjoint-base-change→opfibration L adj =
cartesian+weak-opfibration→opfibration fib $
hom-iso→weak-opfibration L λ u
fibration→hom-iso-from fib u ni∘ (adjunct-hom-iso-from (adj u) _ ni⁻¹)
Expand All @@ -125,8 +125,8 @@ With some repackaging, we can see that this yields a bifibration.
: (L : {x y} (f : Hom x y) Functor (Fibre ℰ x) (Fibre ℰ y))
( {x y} (f : Hom x y) (L f ⊣ base-change f))
is-bifibration
left-adjoint-reindexing→bifibration L adj .is-bifibration.fibration =
left-adjoint-base-change→bifibration L adj .is-bifibration.fibration =
fib
left-adjoint-reindexing→bifibration L adj .is-bifibration.opfibration =
left-adjoint-reindexing→opfibration L adj
left-adjoint-base-change→bifibration L adj .is-bifibration.opfibration =
left-adjoint-base-change→opfibration L adj
```
13 changes: 5 additions & 8 deletions src/Cat/Displayed/Cocartesian/Indexing.lagda.md
Original file line number Diff line number Diff line change
Expand Up @@ -48,21 +48,18 @@ adding in empty fibres.
[the canonical self-indexing]: Cat.Displayed.Instances.Slice.html
[pullbacks]: Cat.Diagram.Pullback.html

Continuing the analogy of indexing as pullback, we call the opreindexing
functors _pushouts_.

```agda
push-out : {x y} (f : Hom x y) Functor (Fibre ℰ x) (Fibre ℰ y)
push-out f .F₀ ob = has-lift.y′ f ob
push-out f .F₁ vert = rebase f vert
cobase-change : {x y} (f : Hom x y) Functor (Fibre ℰ x) (Fibre ℰ y)
cobase-change f .F₀ ob = has-lift.y′ f ob
cobase-change f .F₁ vert = rebase f vert
```

<!--
```agda
push-out f .F-id =
cobase-change f .F-id =
sym $ has-lift.uniquev _ _ _ $ to-pathp $
idl[] ∙ (sym $ cancel _ _ (idr′ _))
push-out f .F-∘ f′ g′ =
cobase-change f .F-∘ f′ g′ =
sym $ has-lift.uniquev _ _ _ $ to-pathp $
smashl _ _
·· revive₁ (pullr[] _ (has-lift.commutesv _ _ _))
Expand Down
10 changes: 6 additions & 4 deletions src/Cat/Displayed/Cocartesian/Weak.lagda.md
Original file line number Diff line number Diff line change
Expand Up @@ -680,13 +680,13 @@ module _ (opfib : Cocartesian-fibration) where
: {x y y′} (u : Hom x y)
natural-iso
(Hom-over-into ℰ u y′)
(Hom-into (Fibre ℰ y) y′ F∘ Functor.op (push-out u) )
(Hom-into (Fibre ℰ y) y′ F∘ Functor.op (cobase-change u) )
opfibration→hom-iso-into {y = y} {y′ = y′} u = to-natural-iso mi where
open make-natural-iso

mi : make-natural-iso
(Hom-over-into ℰ u y′)
(Hom-into (Fibre ℰ y) y′ F∘ Functor.op (push-out u) )
(Hom-into (Fibre ℰ y) y′ F∘ Functor.op (cobase-change u) )
mi .eta x u′ = has-lift.universalv u x u′
mi .inv x v′ = hom[ idl u ] (v′ ∘′ has-lift.lifting u _)
mi .eta∘inv x = funext λ v′
Expand All @@ -703,7 +703,9 @@ module _ (opfib : Cocartesian-fibration) where

opfibration→hom-iso
: {x y} (u : Hom x y)
natural-iso (Hom-over ℰ u) (Hom[-,-] (Fibre ℰ y) F∘ (Functor.op (push-out u) F× Id))
natural-iso
(Hom-over ℰ u)
(Hom[-,-] (Fibre ℰ y) F∘ (Functor.op (cobase-change u) F× Id))
opfibration→hom-iso {y = y} u = to-natural-iso mi where
open make-natural-iso
open _=>_
Expand All @@ -715,7 +717,7 @@ module _ (opfib : Cocartesian-fibration) where

mi : make-natural-iso
(Hom-over ℰ u)
(Hom[-,-] (Fibre ℰ y) F∘ (Functor.op (push-out u) F× Id))
(Hom[-,-] (Fibre ℰ y) F∘ (Functor.op (cobase-change u) F× Id))
mi .eta x u′ = has-lift.universalv u _ u′
mi .inv x v′ = hom[ idl u ] (v′ ∘′ has-lift.lifting u _)
mi .eta∘inv x = funext λ v′
Expand Down

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