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Copyright 2025 The Formal Conjectures Authors.
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-/
module
public import Mathlib.Algebra.Group.Indicator@[expose] public sectionnamespace Setvariable {α R : Type*} [One R] [Zero R] (A : Set α)
A polymorphic indicator function 𝟙_A which is 1 on A and 0 outside.
noncomputable def indicatorOne : α → R := indicator A (fun _ ↦ 1)scoped notation "𝟙_" A:max => indicatorOne Aend Set