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small fixes
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fredrik-bakke committed May 20, 2023
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10 changes: 4 additions & 6 deletions src/foundation-core/propositional-maps.lagda.md
Original file line number Diff line number Diff line change
Expand Up @@ -51,22 +51,20 @@ module _
( is-contr-equiv'
( fib f (f x))
( equiv-fib f (f x))
( is-proof-irrelevant-is-prop (is-prop-map-f (f x)) (pair x refl)))
( λ y ap f)
( is-proof-irrelevant-is-prop (is-prop-map-f (f x)) (x , refl)))
( λ _ ap f)

abstract
is-prop-map-is-emb : is-emb f is-prop-map f
is-prop-map-is-emb is-emb-f y =
is-prop-is-proof-irrelevant α
where
α : (t : fib f y) is-contr (fib f y)
α (pair x refl) =
α (x , refl) =
is-contr-equiv
( fib' f (f x))
( equiv-fib f (f x))
( fundamental-theorem-id'
( λ y ap f)
( λ y is-emb-f x y))
( fundamental-theorem-id' (λ _ ap f) (is-emb-f x))

module _
{l1 l2 : Level} {A : UU l1} {B : UU l2}
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,12 @@ open import synthetic-homotopy-theory.cocones-under-spans

## Idea

A cocone under a span of pointed types is _pointed_ if it consists of pointed
maps such that the proofs of point-preservation cohere.

The type of pointed cocones under a span of pointed types is again canonically
pointed at the constant cocone, with `refl` as coherence proof.

## Definition

```agda
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62 changes: 31 additions & 31 deletions src/synthetic-homotopy-theory/wedges-of-pointed-types.lagda.md
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
# Wedges of types
# Wedges of pointed types

```agda
module synthetic-homotopy-theory.wedges-of-pointed-types where
Expand All @@ -8,6 +8,7 @@ module synthetic-homotopy-theory.wedges-of-pointed-types where

```agda
open import foundation.dependent-pair-types
open import foundation.embeddings
open import foundation.homotopies
open import foundation.identity-types
open import foundation.universe-levels
Expand All @@ -27,17 +28,17 @@ open import synthetic-homotopy-theory.pushouts-of-pointed-types
## Idea

The **wedge** or **wedge sum** of two pointed types `a : A` and `b : B` is
defined by the following pushout.
defined by the following pointed pushout:

```text
unit ------> A
| |
| |
v ⌜ v
B -----> A ∨∗ B
B -----> A ∨∗ B,
```

The wedge sum is canonically pointed at the (identified) images of `a` and `b`.
and is thus canonically pointed at the identified image of `a` and `b`.

## Definition

Expand Down Expand Up @@ -68,38 +69,37 @@ pr2 (indexed-wedge I A) = point-cofiber (λ i → i , point-Pointed-Type (A i))

## Properties

### The canonical inclusion of the wedge sum `A ∨∗ B` into the pointed product `A ×∗ B`
### The inclusion of the wedge sum `A ∨∗ B` into the pointed product `A ×∗ B`

There is a canonical inclusion of the wedge sum into the pointed product that is
defined by the cogap map induced by the canonical inclusions `A A ×∗ B B`.

```agda
cocone-prod-wedge-Pointed-Type :
{l1 l2 : Level} (A : Pointed-Type l1) (B : Pointed-Type l2)
type-cocone-Pointed-Type
( inclusion-point-Pointed-Type A)
( inclusion-point-Pointed-Type B)
( A ×∗ B)
pr1 (cocone-prod-wedge-Pointed-Type A B) = inl-prod-Pointed-Type A B
pr1 (pr2 (cocone-prod-wedge-Pointed-Type A B)) = inr-prod-Pointed-Type A B
pr1 (pr2 (pr2 (cocone-prod-wedge-Pointed-Type A B))) = refl-htpy
pr2 (pr2 (pr2 (cocone-prod-wedge-Pointed-Type A B))) = refl

pointed-map-prod-wedge-Pointed-Type :
{l1 l2 : Level}
(A : Pointed-Type l1) (B : Pointed-Type l2)
(A ∨∗ B) →∗ (A ×∗ B)
pointed-map-prod-wedge-Pointed-Type A B =
cogap-Pointed-Type
( inclusion-point-Pointed-Type A)
( inclusion-point-Pointed-Type B)
( cocone-prod-wedge-Pointed-Type A B)

map-prod-wedge-Pointed-Type :
{l1 l2 : Level}
(A : Pointed-Type l1) (B : Pointed-Type l2)
type-Pointed-Type (A ∨∗ B) type-Pointed-Type (A ×∗ B)
map-prod-wedge-Pointed-Type A B = pr1 (pointed-map-prod-wedge-Pointed-Type A B)
module _
{l1 l2 : Level} (A : Pointed-Type l1) (B : Pointed-Type l2)
where

cocone-prod-wedge-Pointed-Type :
type-cocone-Pointed-Type
( inclusion-point-Pointed-Type A)
( inclusion-point-Pointed-Type B)
( A ×∗ B)
pr1 cocone-prod-wedge-Pointed-Type = inl-prod-Pointed-Type A B
pr1 (pr2 cocone-prod-wedge-Pointed-Type) = inr-prod-Pointed-Type A B
pr1 (pr2 (pr2 cocone-prod-wedge-Pointed-Type)) = refl-htpy
pr2 (pr2 (pr2 cocone-prod-wedge-Pointed-Type)) = refl

pointed-map-prod-wedge-Pointed-Type :
(A ∨∗ B) →∗ (A ×∗ B)
pointed-map-prod-wedge-Pointed-Type =
cogap-Pointed-Type
( inclusion-point-Pointed-Type A)
( inclusion-point-Pointed-Type B)
( cocone-prod-wedge-Pointed-Type)

map-prod-wedge-Pointed-Type :
type-Pointed-Type (A ∨∗ B) type-Pointed-Type (A ×∗ B)
map-prod-wedge-Pointed-Type = pr1 pointed-map-prod-wedge-Pointed-Type
```

## See also
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