English
If i ≠ j are distinct roots in the base b, then P.root i ≠ −P.root j.
Русский
Если i ≠ j — корни базиса b, то P.root i ≠ −P.root j.
LaTeX
$$$\\text{If } i,j\\in b.support,\\ i\\neq j, \\text{ then } P.root(i) \\neq -P.root(j).$$$
Lean4
theorem root_ne_neg_of_ne [Nontrivial R] {i j : ι} (hi : i ∈ b.support) (hj : j ∈ b.support) (hij : i ≠ j) :
P.root i ≠ -P.root j := by
classical
intro contra
have :=
linearIndepOn_iff'.mp b.linearIndepOn_root ({ i, j } : Finset ι) 1 (by simp [Set.insert_subset_iff, hi, hj])
(by simp [Finset.sum_pair hij, contra])
simp_all