diff --git a/CHANGELOG.md b/CHANGELOG.md index 12039b4aed..99616b2df2 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -180,6 +180,11 @@ Additions to existing modules contradiction′ : ¬ A → A → Whatever ``` +* In `Relation.Unary` + ```agda + _⊣_ : (A → B) → Pred A ℓ → Pred B _ + ``` + * In `System.Random`: ```agda randomIO : IO Bool diff --git a/src/Relation/Unary.agda b/src/Relation/Unary.agda index 86bb80f1bb..a36547affd 100644 --- a/src/Relation/Unary.agda +++ b/src/Relation/Unary.agda @@ -202,7 +202,7 @@ Decidable P = ∀ x → Dec (P x) -- Operations on sets infix 10 ⋃ ⋂ -infixr 9 _⊢_ +infixr 9 _⊢_ _⊣_ infixr 8 _⇒_ infixr 7 _∩_ infixr 6 _∪_ @@ -266,6 +266,11 @@ P ⊥′ Q = P ∩ Q ⊆′ ∅ _⊢_ : (A → B) → Pred B ℓ → Pred A ℓ f ⊢ P = λ x → P (f x) +-- Pushforward. + +_⊣_ : (A → B) → Pred A ℓ → Pred B _ +f ⊣ P = λ b → ∃ λ a → f a ≡ b × P a + ------------------------------------------------------------------------ -- Predicate combinators