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Lower and Upper Lie Nilpotency Indices of Modular Group Algebras
Abstract
We resolve the remaining cases of a longstanding problem on the lower and upper Lie nilpotency indices of modular group algebras. Equality of the two indices has been known in characteristics greater than three since 1992; we establish it in the remaining characteristics two and three, thereby completing the problem for finite groups of prime-power order over finite fields. The proof gives a uniform argument for every prime and introduces a terminal restricted Poincare-Birkhoff-Witt construction that converts the lower-Lie problem into a chronological reachability argument, with no structural hypothesis on the derived subgroup.
Related
BibTeX
@misc{gildea2026lower,
title = {{Lower and Upper Lie Nilpotency Indices of Modular Group Algebras}},
author = {Joe Gildea},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.10915},
eprint = {2610.10915},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.10915},
}
RIS
TY - UNPB
TI - Lower and Upper Lie Nilpotency Indices of Modular Group Algebras
AU - Joe Gildea
PY - 2026
DA - 2026/10/07
PB - arXiv
DO - 10.48550/arxiv.2610.10915
UR - https://arxiv.org/abs/2610.10915
AB - We resolve the remaining cases of a longstanding problem on the lower and upper Lie nilpotency indices of modular group algebras. Equality of the two indices has been known in characteristics greater than three since 1992; we establish it in the remaining characteristics two and three, thereby completing the problem for finite groups of prime-power order over finite fields. The proof gives a uniform argument for every prime and introduces a terminal restricted Poincare-Birkhoff-Witt construction that converts the lower-Lie problem into a chronological reachability argument, with no structural hypothesis on the derived subgroup.
ER -