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Mathlib.RingTheory.Finiteness.Cardinality

Finite modules and types with finitely many elements #

This file relates Module.Finite and _root_.Finite.

theorem Module.Finite.exists_fin' (R : Type u_1) (M : Type u_4) [Semiring R] [AddCommMonoid M] [Module R M] [Module.Finite R M] :
∃ (n : ) (f : (Fin nR) →ₗ[R] M), Function.Surjective f
theorem Module.finite_of_finite (R : Type u_1) {M : Type u_4} [Semiring R] [AddCommMonoid M] [Module R M] [Finite R] [Module.Finite R M] :
@[deprecated Module.finite_of_finite]
theorem FiniteDimensional.finite_of_finite (R : Type u_1) {M : Type u_4} [Semiring R] [AddCommMonoid M] [Module R M] [Finite R] [Module.Finite R M] :

Alias of Module.finite_of_finite.

@[deprecated Module.finite_of_finite]
theorem FiniteDimensional.fintypeOfFintype (R : Type u_1) {M : Type u_4} [Semiring R] [AddCommMonoid M] [Module R M] [Finite R] [Module.Finite R M] :

A finite dimensional vector space over a finite field is finite

theorem Module.finite_iff_finite {R : Type u_1} {M : Type u_4} [Semiring R] [AddCommMonoid M] [Module R M] [Finite R] :

A module over a finite ring has finite dimension iff it is finite.

theorem Set.Finite.submoduleSpan (R : Type u_1) {M : Type u_4} [Semiring R] [AddCommMonoid M] [Module R M] [Finite R] {s : Set M} (hs : s.Finite) :
(↑(Submodule.span R s)).Finite
theorem Module.Finite.finite_basis {R : Type u_1} {M : Type u_4} [Semiring R] [AddCommMonoid M] [Module R M] [Nontrivial R] {ι : Type u_6} [Module.Finite R M] (b : Basis ι R M) :

If a free module is finite, then any arbitrary basis is finite.