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Integral models of toroidal compactifications with projective cone decompositions. (English) Zbl 1405.14124

Summary: We construct integral models of toroidal compactifications of PEL-type Shimura varieties with projective cone decompositions as normalizations of certain explicit blowups of the corresponding minimal compactifications, generalizing works of A. Ash’s et al. [Smooth compactification of locally symmetric varieties. Lie Groups: History, Frontiers and Applications. Vol. IV. Brookline, Mass.: Math Sci Press (1975; Zbl 0334.14007)], C.-L. Chai’s [“Compactification of Siegel moduli schemes”, Lond. Math. Soc. Lect. Note Ser. 107 (1985; Zbl 0578.14009)], G. Faltings and C.-L. Chai’s [Degeneration of abelian varieties. Berlin etc.: Springer-Verlag (1990; Zbl 0744.14031)], and the author’s [Arithmetic compactifications of PEL-type Shimura varieties. Princeton, NJ: Princeton University Press (2013; Zbl 1284.14004)] in zero or good reduction characteristics. We show that such integral models still enjoy many features of the good reduction theory, regardless of the levels and ramifications involved.

MSC:

14M27 Compactifications; symmetric and spherical varieties
14G35 Modular and Shimura varieties