English
If two LieDerivations agree on a set s, they agree on the Lie span of s as well.
Русский
Если два LieDerivation совпадают на наборе s, они совпадают на Lie-образе s.
LaTeX
$$$\text{If } \text{EqOn } D_1 D_2 s, \text{ then } \text{EqOn } D_1 D_2(\operatorname{lieSpan} R L s)$$$
Lean4
/-- Two Lie derivations equal on a set are equal on its Lie span. -/
theorem eqOn_lieSpan {s : Set L} (h : Set.EqOn D1 D2 s) : Set.EqOn D1 D2 (LieSubalgebra.lieSpan R L s) :=
by
intro _ hx
induction hx using LieSubalgebra.lieSpan_induction with
| mem x hx => exact h hx
| zero => simp
| add x y _ _ hx hy => simp [hx, hy]
| smul t x _ hx => simp [hx]
| lie x y _ _ hx hy => simp [hx, hy]