English
A flat R-module M is equivalent to injectivity of all lTensor variants with I-subtype.
Русский
Плоскость M эквивалентна инъективности всех вариаций lTensor с I-subtype.
LaTeX
$$$\\text{Flat}(R,M) \\iff \\forall I, \\text{FG} \\rightarrow \\text{Injective}(\\mathrm{lTensor}(M, I.subtype))$$$
Lean4
/-- The `lTensor`-variant of `iff_rTensor_injective'`. . -/
theorem iff_lTensor_injective' : Flat R M ↔ ∀ (I : Ideal R), Function.Injective (lTensor M I.subtype) := by
simpa [← comm_comp_rTensor_comp_comm_eq] using iff_rTensor_injective'