Central extensions of rank 2 groups and applications
نویسندگان
چکیده
We show that the universal central extensions of the little projective group of any Moufang polygon is precisely the Steinberg group obtained from its defining commutator relations, provided the defining structure is not too small. As an application, we get that also the universal central extensions of the little projective group of any 2-spherical Moufang twin building is precisely the Steinberg group obtained from its defining commutator relations. MSC-2000 : primary: 19C09, 51E24 ; secondary: 20E42, 51E12 keywords : central extensions, Moufang polygons, buildings, Steinberg relations, commutator relations
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