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authorChloe Brown <chloe.brown.00@outlook.com>2022-01-05 18:02:53 +0000
committerChloe Brown <chloe.brown.00@outlook.com>2022-01-05 18:02:53 +0000
commit1361fa660294004d4b231211102d681e6c3fc4c9 (patch)
tree0c4e275e6d8b2475c50df7489223e18bf9f18492
parent2bc5a95f09b8f2f3537489a19254d9896bf47c7c (diff)
I: 4: b: show monomorphisms compose
-rw-r--r--src/CatTheory/Morphism/Properties.agda4
1 files changed, 4 insertions, 0 deletions
diff --git a/src/CatTheory/Morphism/Properties.agda b/src/CatTheory/Morphism/Properties.agda
index ef560f9..ffae923 100644
--- a/src/CatTheory/Morphism/Properties.agda
+++ b/src/CatTheory/Morphism/Properties.agda
@@ -63,3 +63,7 @@ Retract⇒Mono {g = g} {f = f} g∘f≈id h₁ h₂ f∘h₁≈f∘h₂ = begin
g ∘ (f ∘ h₁) ≈⟨ refl⟩∘⟨ f∘h₁≈f∘h₂ ⟩
g ∘ (f ∘ h₂) ≈⟨ cancelˡ g∘f≈id ⟩
h₂ ∎
+
+Mono∘ : Mono f → Mono g → Mono (f ∘ g)
+Mono∘ {f = f} {g = g} f-mono g-mono h₁ h₂ f∘g∘h₁≈f∘g∘h₂ =
+ g-mono h₁ h₂ $ f-mono (g ∘ h₁) (g ∘ h₂) $ sym-assoc ○ f∘g∘h₁≈f∘g∘h₂ ○ assoc