High-Degree Restricted Cohomology for K(3;1)(1) in Characteristics Five and Seven
Abstract
We determine the high-degree restricted first cohomology of the positive subalgebra of the rank-one contact algebra in characteristics five and seven, with parabolically induced coefficients. In degrees from twice the characteristic through four times the characteristic minus three, each characteristic has six nonzero homogeneous components, of total dimension thirteen. The constituents include Frobenius twists of the natural horizontal module, represented by Cartier cocycles. PBW duality converts the calculation into bounded-degree homology, where the coefficient action couples the natural and cubic relation coordinates. The resulting modules determine the high-degree part of the coefficient cohomology used in the Lyndon-Hochschild-Serre term E20,1 for extensions of induced contact modules. In particular, extensions from the Steinberg induced modules vanish in these degrees.
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BibTeX
@misc{ma2026highdegree,
title = {{High-Degree Restricted Cohomology for $K(3;1)^(1)$ in Characteristics Five and Seven}},
author = {Chao Ma},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.06396},
eprint = {2611.06396},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.06396},
}
RIS
TY - UNPB
TI - High-Degree Restricted Cohomology for K(3;1)^(1) in Characteristics Five and Seven
AU - Chao Ma
PY - 2026
DA - 2026/11/04
PB - arXiv
DO - 10.48550/arxiv.2611.06396
UR - https://arxiv.org/abs/2611.06396
AB - We determine the high-degree restricted first cohomology of the positive subalgebra of the rank-one contact algebra in characteristics five and seven, with parabolically induced coefficients. In degrees from twice the characteristic through four times the characteristic minus three, each characteristic has six nonzero homogeneous components, of total dimension thirteen. The constituents include Frobenius twists of the natural horizontal module, represented by Cartier cocycles. PBW duality converts the calculation into bounded-degree homology, where the coefficient action couples the natural and cubic relation coordinates. The resulting modules determine the high-degree part of the coefficient cohomology used in the Lyndon-Hochschild-Serre term E_2^0,1 for extensions of induced contact modules. In particular, extensions from the Steinberg induced modules vanish in these degrees.
ER -