English
If a lies in the adjoin of {f, g} with f and g semisimple and commuting, then a is semisimple.
Русский
Если a лежит в адъюнкте {f, g} и f, g семисемпсимы и commute, тогда a семисемпсим.
LaTeX
$$$ Commute(f,g) \land IsSemisimple(f) \land IsSemisimple(g) \Rightarrow \forall a \in \mathrm{algebra\ adjoin}_K(\{f,g\}), IsSemisimple(a)$$$
Lean4
protected theorem pow (n : ℕ) : (f ^ n).IsSemisimple :=
.of_mem_adjoin_singleton hf (pow_mem (Algebra.self_mem_adjoin_singleton _ _) _)