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Theorems · Theorem · combinatorics

Finset.le_card_of_inj_on_range

∀ {α : Type u_1} {s : Finset α} {n : ℕ} (f : ℕ → α),
  (∀ i < n, f i ∈ s) → (∀ i < n, ∀ j < n, f i = f j → i = j) → n ≤ s.card

See also Finset.card_le_card_of_injOn, which is a more general version of this lemma. TODO: consider deprecating, since this is just a special case of Finset.card_le_card_of_injOn.

Defined in
Mathlib.Data.Finset.Card
Cited by
3 results in Mathlib
Foundations
Depth 80 from the axioms · uses propext, Classical.choice, Quot.sound

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