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The algebraic K-theory of k[SL2(π½q)]
Abstract
We compute via trace methods the higher algebraic K-theory of the group ring k[SL2(π½q)], as well as the related groups PSL2(π½q), PGL2(π½q), and GL2(π½q), where k is a finite field of characteristic p and q=pr. At the core of the computation is the algebraic K-theory of the group ring of the Sylow p-subgroup, k[Cpr], which we determine via a theorem of LΓΌck--Reich--Rognes--Varisco on cyclic assembly for topological cyclic homology. In the process, we reprove the cyclic assembly result in the language of Nikolaus--Scholze, analyse assembly for smaller families of subgroups, and develop further tools for computing topological cyclic homology of group rings.
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BibTeX
@misc{moselle2026algebraic,
title = {{The algebraic K-theory of $k[\operatornameSL_2(\mathbbF_q)]$}},
author = {Isaac Moselle},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2606.21421},
eprint = {2606.21421},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.21421},
}
RIS
TY - UNPB
TI - The algebraic K-theory of k[SL_2(π½_q)]
AU - Isaac Moselle
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2606.21421
UR - https://arxiv.org/abs/2606.21421
AB - We compute via trace methods the higher algebraic K-theory of the group ring k[SL_2(π½_q)], as well as the related groups PSL_2(π½_q), PGL_2(π½_q), and GL_2(π½_q), where k is a finite field of characteristic p and q=p^r. At the core of the computation is the algebraic K-theory of the group ring of the Sylow p-subgroup, k[C_p^r], which we determine via a theorem of LΓΌck--Reich--Rognes--Varisco on cyclic assembly for topological cyclic homology. In the process, we reprove the cyclic assembly result in the language of Nikolaus--Scholze, analyse assembly for smaller families of subgroups, and develop further tools for computing topological cyclic homology of group rings.
ER -