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SphereEversion.ToMathlib.LinearAlgebra.FiniteDimensional

theorem one_lt_rank_of_rank_lt_rank {𝕜 : Type u_1} [Field 𝕜] {E : Type u_2} [AddCommGroup E] [Module 𝕜 E] {E' : Type u_3} [AddCommGroup E'] [Module 𝕜 E'] [FiniteDimensional 𝕜 E] [FiniteDimensional 𝕜 E'] {π : E →ₗ[𝕜] 𝕜} ( : π.ker ) (h : Module.finrank 𝕜 E < Module.finrank 𝕜 E') (φ : E →ₗ[𝕜] E') :
1 < Module.rank 𝕜 (E' Submodule.map φ π.ker)