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Nonzero finite dimension under nontriviality

Definition
KLSModular_BrownianMotion_Auxiliary_Algebra

by Lazyfill · Oct 25, 2026 · Mathlib 0df444a (Lean v4.33.1)

functional-inequalitiesklskls-conjecturekls-modularlog-concavemodule-contextvendored-brownianmotion

Vendored from RemyDegenne/brownian-motion at commit a7ad7af662044313bc80a7c0756360fb3745f931, with a local Mathlib compatibility patch under Apache-2.0. Module.finrank_ne_zero states that the module rank over a domain is nonzero when the module is finite, torsion-free, and nontrivial; the bundle also registers the zero-dimensional simplification for subsingleton modules.

Original module imports

public import Mathlib.LinearAlgebra.Dimension.Finite

Original declaration excerpt

Shown in the original module context.

@[simp]
lemma Module.finrank_ne_zero {R M : Type*} [Ring R] [AddCommGroup M] [Module R M]
    [StrongRankCondition R] [Module.Finite R M] [IsDomain R] [IsTorsionFree R M]
    [h : Nontrivial M] :
    finrank R M ≠ 0 := finrank_pos.ne'

Module navigation

Project result: The KLS conjecture.

Original module · BrownianMotion.Auxiliary.Algebra · Frozen source 408915f.

Definition code
import Mathlib.LinearAlgebra.Dimension.Finite

-- Modified by kls-lean for Lean/Mathlib v4.33.0; see formalization/vendor/port.patch.
-- Vendored from https://github.com/RemyDegenne/brownian-motion at commit a7ad7af662044313bc80a7c0756360fb3745f931 (upstream path BrownianMotion/Auxiliary/Algebra.lean; Apache-2.0; locally patched, see formalization/vendor/port.patch; provenance in formalization/vendor/vendor-lock.json of the KLS repository)
section
attribute [simp] Module.finrank_zero_of_subsingleton
@[simp]
lemma Module.finrank_ne_zero {R M : Type*} [Ring R] [AddCommGroup M] [Module R M]
    [StrongRankCondition R] [Module.Finite R M] [IsDomain R] [IsTorsionFree R M]
    [h : Nontrivial M] :
    finrank R M ≠ 0 := finrank_pos.ne'
open Finset
Source
Lean source: https://github.com/RemyDegenne/brownian-motion/blob/a7ad7af662044313bc80a7c0756360fb3745f931/BrownianMotion/Auxiliary/Algebra.lean (repository human-ai-mathematics/kls-lean, commit 408915f, module `BrownianMotion.Auxiliary.Algebra`, definition bundle `KLSModular_BrownianMotion_Auxiliary_Algebra`; the repository is private at upload time); vendored copy patched by formalization/vendor/port.patch (project file formalization/vendor/BrownianMotion/BrownianMotion/Auxiliary/Algebra.lean, lines 29-33). Vendored from https://github.com/RemyDegenne/brownian-motion at commit a7ad7af662044313bc80a7c0756360fb3745f931 (Apache-2.0; upstream copyright notice retained in the Lean text).

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