Das Titsgebaeude von Siegelschen Modulgruppen vom Geschlecht 2
arXiv:math/0002249
Abstract
We calculate Tits buildings for certain arithmetic subgroups of Sp(4). These give information about the boundary of the corresponding moduli spaces of abelian surfaces. More pictures (in colour) and a summary of the results (in English) can be found at http://www.bath.ac.uk/~masgks/Buildings/
22 pages, 4 figures. LaTeX, epsfig, German. Minor corrections. To appear in Abh. Math. Sem. Univ. Hamburg