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Theorems · Theorem · combinatorics

Sym.card_sym_eq_choose

∀ {α : Type u_2} [inst : Fintype α] (k : ℕ) [inst_1 : Fintype (Sym α k)],
  Fintype.card (Sym α k) = (Fintype.card α + k - 1).choose k

The stars and bars lemma: the cardinality of Sym α k is equal to Nat.choose (card α + k - 1) k.

Defined in
Mathlib.Data.Sym.Card
Cited by
1 results in Mathlib
Foundations
Depth 84 from the axioms · uses propext, Classical.choice, Quot.sound
Assumes
FintypeFintype

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