English

Schur multiplier of $\mathrm{SL}_2$ over finite commutative rings

K-Theory and Homology 2025-10-07 v1 Group Theory

Abstract

In this article, we investigate the Schur multiplier of the special linear group SL2(A)\mathrm{SL}_2(A) over finite commutative local rings AA. We prove that the Schur multiplier of these groups is isomorphic to the KK-group K2(A)K_2(A) whenever the residue field A/mAA/\mathfrak{m}_A has odd characteristic and satisfies A/mA3,5,9|A/\mathfrak{m}_A| \neq 3,5,9. As an application, we show that if AA is either the Galois ring GR(pl,m)\mathrm{GR}(p^l,m) or the quasi-Galois ring A(pm,n)A(p^m,n) with residue field of odd characteristic and A/mA3,5,9|A/\mathfrak{m}_A| \neq 3,5,9, then the Schur multiplier of SL2(A)\mathrm{SL}_2(A) is trivial.

Keywords

Cite

@article{arxiv.2510.03946,
  title  = {Schur multiplier of $\mathrm{SL}_2$ over finite commutative rings},
  author = {Behrooz Mirzaii and Abraham Rojas Vega},
  journal= {arXiv preprint arXiv:2510.03946},
  year   = {2025}
}

Comments

40 pages