$A_3$-formality for Demushkin groups at odd primes
Group Theory
2026-01-23 v2 Algebraic Topology
K-Theory and Homology
Number Theory
Abstract
We study a weak form of formality for differential graded algebras, called -formality, for the cohomology of pro-p Demushkin groups at odd primes p. We show that the differential graded -algebras of continuous cochains of Demushkin groups with q-invariant not equal 3 are -formal, whereas Demushkin groups with q-invariant 3 are not -formal. We prove these results by an explicit computation of the Benson-Krause-Schwede canonical class in Hochschild cohomology.
Cite
@article{arxiv.2601.07551,
title = {$A_3$-formality for Demushkin groups at odd primes},
author = {Ambrus Pál and Gereon Quick},
journal= {arXiv preprint arXiv:2601.07551},
year = {2026}
}
Comments
v2: 46 pages; update of the presentation of prior results in the introduction, references added