Theorems · Theorem · combinatorics

Finset.pimage_eq_image_filter

∀ {α : Type u_1} {β : Type u_2} [inst : DecidableEq β] {f : α →. β} [inst_1 : (x : α) → Decidable (f x).Dom]
  {s : Finset α}, Finset.pimage f s = Finset.image (fun x => (f ↑x).get ⋯) {x ∈ s | (f x).Dom}.attach

Rewrite s.pimage f in terms of Finset.filter, Finset.attach, and Finset.image.

Defined in

Mathlib.Data.Finset.PImage

Cited by

0 results in Mathlib

Foundations

Depth 78 from the axioms · uses propext, Classical.choice, Quot.sound

Assumes

DecidableEqDecidable