In studying nilpotent groups, the lower central series and other variations can be used to construct an associated ℤ+-graded Lie ring, which is a powerful method to inspect a group. Indeed, the process can be generalized substantially by introducing ℕd-graded Lie rings. We compute the adjoint refinements of the lower central series of the unipotent subgroups of the classical Chevalley groups over the field ℤ/pℤ of rank d. We prove that, for all the classical types, this characteristic filter is a series of length Θ(d2) with nearly all factors having p-bounded order.
The author is indebted to J. B. Wilson for suggesting and advising this project, A. Hulpke for helpful discussions and coding advice, and the referee for insightful comments which improved the clarity of the paper.
© 2015 by De Gruyter