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Unitary Steinberg group is centrally closed. / Lavrenov, A.
в: St. Petersburg Mathematical Journal, Том 24, № 5, 2013, стр. 783--794.Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
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TY - JOUR
T1 - Unitary Steinberg group is centrally closed
AU - Lavrenov, A.
PY - 2013
Y1 - 2013
N2 - Let (R,Lambda) be an arbitrary form ring, U(2n,R,Lambda) be the hyperbolic unitary group, EU(2n,R,Lambda) be its elementary subgroup and StU(2n,R,Lambda) be the unitary Steinberg group. We prove that under natural assumption n>=5 every central extension of StU(2n,R,Lambda) splits. Using this result in the situation when the kernel of natural epimorphism from StU(2n,R,Lambda) onto EU(2n,R,Lambda) is contained in the center of StU(2n,R,Lambda) we obtain that this kernel coincides with the Schur multiplier of the elementary unitary group. We use Steinberg relation from the paper~[10] to obtain the most simple proofs of these results.
AB - Let (R,Lambda) be an arbitrary form ring, U(2n,R,Lambda) be the hyperbolic unitary group, EU(2n,R,Lambda) be its elementary subgroup and StU(2n,R,Lambda) be the unitary Steinberg group. We prove that under natural assumption n>=5 every central extension of StU(2n,R,Lambda) splits. Using this result in the situation when the kernel of natural epimorphism from StU(2n,R,Lambda) onto EU(2n,R,Lambda) is contained in the center of StU(2n,R,Lambda) we obtain that this kernel coincides with the Schur multiplier of the elementary unitary group. We use Steinberg relation from the paper~[10] to obtain the most simple proofs of these results.
KW - Unitary Steinberg group
KW - Schur multiplier
KW - unitary group
KW - form parameter
KW - non-stable K-theory
M3 - статья
VL - 24
SP - 783
EP - 794
JO - St. Petersburg Mathematical Journal
JF - St. Petersburg Mathematical Journal
SN - 1061-0022
IS - 5
ER -
ID: 5676281