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Tashi Walde committed Oct 13, 2023
2 parents 127eda9 + c3bc89a commit d30e656
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4 changes: 2 additions & 2 deletions src/hott/03-equivalences.rzk.md
Original file line number Diff line number Diff line change
Expand Up @@ -535,8 +535,8 @@ The retraction associated with an equivalence is an equivalence.

## Section-retraction pairs

A pair of maps `s : A' → B` and `r : B → A` is a section-retraction pair if the
composite `A' → A` is an equivalence.
A pair of maps `s : A' → B` and `r : B → A` is a **section-retraction pair** if
the composite `A' → A` is an equivalence.

```rzk
#section is-section-retraction-pair
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14 changes: 7 additions & 7 deletions src/hott/08-families-of-maps.rzk.md
Original file line number Diff line number Diff line change
Expand Up @@ -318,35 +318,35 @@ The canonical map from a type to its the free path type is an equivalence.
#def free-paths
( A : U)
: U
:= Σ ( (x, y) : product A A) , (x = y)
:= Σ ( (x , y) : product A A) , (x = y)
#def constant-free-path
( A : U)
( a : A)
: free-paths A
:= ((a,a), refl)
:= ((a , a) , refl)
#def is-constant-free-path
( A : U)
( ((a,y), p) : free-paths A)
( ((a , y) , p) : free-paths A)
: constant-free-path A a = ((a,y), p)
:=
ind-path A a
( \ x p' → constant-free-path A a = ((a,x), p'))
( \ x p' → constant-free-path A a = ((a , x) , p'))
( refl)
( y) ( p)
#def start-free-path
( A : U)
: free-paths A → A
:= \ ((a,_), _) → a
:= \ ((a , _) , _) → a
#def is-equiv-constant-free-path
( A : U)
: is-equiv A (free-paths A) (constant-free-path A)
:=
( ( start-free-path A, \ _ → refl)
, ( start-free-path A, is-constant-free-path A))
( ( start-free-path A , \ _ → refl)
, ( start-free-path A , is-constant-free-path A))
```

## Pullback of a type family
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14 changes: 7 additions & 7 deletions src/simplicial-hott/05-segal-types.rzk.md
Original file line number Diff line number Diff line change
Expand Up @@ -238,20 +238,20 @@ type.
#def fibered-arr-free-arr
( A : U)
: (arr A)(fibered-arr A)
: arr A → fibered-arr A
:= \ k → (k 0₂ , (k 1₂ , k))
#def is-equiv-fibered-arr-free-arr
( A : U)
: is-equiv (arr A) (fibered-arr A) (fibered-arr-free-arr A)
:=
( ( \ (_ , (_ , f)) → f , \ _ → refl)
, ( \ (_ , (_ , f)) → f , \ _ → refl))
( ( (\ (_ , (_ , f)) → f) , (\ _ → refl))
, ( (\ (_ , (_ , f)) → f) , (\ _ → refl)))
#def equiv-fibered-arr-free-arr
( A : U)
: Equiv (arr A) (fibered-arr A)
:= ( fibered-arr-free-arr A , is-equiv-fibered-arr-free-arr A)
:= (fibered-arr-free-arr A , is-equiv-fibered-arr-free-arr A)
```

And the corresponding uncurried version.
Expand All @@ -266,14 +266,14 @@ And the corresponding uncurried version.
#def fibered-arr-free-arr'
( A : U)
: arr A → fibered-arr' A
:= \ σ → ((σ 0₂, σ 1₂), σ)
:= \ σ → ((σ 0₂ , σ 1₂) , σ)
#def is-equiv-fibered-arr-free-arr'
( A : U)
: is-equiv (arr A) (fibered-arr' A) (fibered-arr-free-arr' A)
:=
( ( \ ((_ , _) , σ) → σ , \ _ → refl)
, ( \ ((_ , _) , σ) → σ , \ _ → refl))
( ( (\ ((_ , _) , σ) → σ) , (\ _ → refl))
, ( (\ ((_ , _) , σ) → σ) , (\ _ → refl)))
```

## The Segal condition
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