5-Engel Lie algebras II

Abstract: In my article 5-Engel algebras published on the arXiv in 2023 I proved that 5-Engel Lie algebras of characteristic zero or prime characteristic $p>7$ are nilpotent of class at most 11. In this note I investigate the ideal ID$(x)$ generated by an element $x$ in a 5-Engel Lie algebra. In characteristic 2 and 3 this ideal does not have to be nilpotent. For all primes $p>3$ I show that Id$(x)$ is nilpotent in 5-Engel Lie algebras of characteristic $p$, and I obtain explicit (best possible) bounds on the nilpotency class.