English
If i, j are indices with P.root i + P.root j in the range of P.root, then {P.root i, P.root j} is linearly independent.
Русский
Если i, j удовлетворяют P.root i + P.root j ∈ range(P.root), то {P.root i, P.root j} линейно независимо.
LaTeX
$$$$ (P.root i + P.root j) \\in \\operatorname{range}(P.root) \\Rightarrow \\operatorname{LI}_R(\\![P.root i, P.root j]\\!). $$$$
Lean4
theorem linearIndependent_of_add_mem_range_root [CharZero R] [NoZeroSMulDivisors ℤ M] [P.IsReduced] {i j : ι}
(h : P.root i + P.root j ∈ range P.root) : LinearIndependent R ![P.root i, P.root j] :=
by
refine IsReduced.linearIndependent P (fun hij ↦ ?_) (fun hij ↦ P.zero_notMem_range_root ?_)
· rw [hij, ← two_smul (R := ℕ)] at h
exact P.nsmul_notMem_range_root h
· rwa [hij, neg_add_cancel] at h