`BookProof.ChapterFreeFieldBornSignOrientationSubgroup.orientationPreservingSigns_index` (n : ℕ) : (orientationPreservingSigns (n + 1)).index = 2

Initializing...

`BookProof.ChapterFreeFieldBornSignOrientationSubgroup.orientationPreservingSigns_index` (n : ℕ) : (orientationPreservingSigns (n + 1)).index = 2 · Prove2Me