Abstract
We determine the group presentations of universal central extensions derived from loop groups, where loop groups are Chevalley groups over Laurent polynomial rings. We also show that the universal central extensions have Tits systems. For our purpose, we introduce additive Steinberg symbols.
Citation
Yasutomo Asai. "Loop groups SL2(F[X;X−1]), universal central extensions and additive Steinberg symbols." Tsukuba J. Math. 36 (1) 79 - 97, July 2012. https://doi.org/10.21099/tkbjm/1341951746
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