Theorems · Definition · logic and foundations

Set.preimage

{α : Type u} → {β : Type v} → (α → β) → Set β → Set α

The preimage of s : Set β by f : α → β, written f ⁻¹' s, is the set of x : α such that f x ∈ s.

Defined in

Mathlib.Data.Set.Operations

Cited by

4,946 results in Mathlib

Foundations

Depth 4 from the axioms, rests on 8 definitions · uses no axioms