Existence of embeddings from finite types #
Let s : Set α be a finite set.
Fin.Embedding.exists_embedding_disjoint_range_of_add_le_ENat_cardIfs.ncard + n ≤ ENat.card α, then there exists an embeddingFin n ↪ αwhose range is disjoint froms.Fin.Embedding.exists_embedding_disjoint_range_of_add_le_Nat_cardIfαis finite ands.ncard + n ≤ Nat.card α, then there exists an embeddingFin n ↪ αwhose range is disjoint froms.Fin.Embedding.restrictSurjective_of_add_le_ENatCardIfm + n ≤ ENat.card α, then the restriction map fromFin (m + n) ↪ αtoFin m ↪ αis surjective.Fin.Embedding.restrictSurjective_of_add_le_natCardIfαis finite andm + n ≤ Nat.card α, then the restriction map fromFin (m + n) ↪ αtoFin m ↪ αis surjective.
theorem
Fin.Embedding.restrictSurjective_of_add_le_ENatCard
{α : Type u_1}
{m n : ℕ}
(hn : ↑m + ↑n ≤ ENat.card α)
:
Function.Surjective fun (x : Fin (m + n) ↪ α) => (castAddEmb n).trans x
theorem
Fin.Embedding.restrictSurjective_of_add_le_natCard
{α : Type u_1}
{m n : ℕ}
[Finite α]
(hn : m + n ≤ Nat.card α)
:
Function.Surjective fun (x : Fin (m + n) ↪ α) => (castAddEmb n).trans x