Smoothings and rational double point adjacencies for cusp singularities

نویسندگان

چکیده

A cusp singularity is a surface whose minimal resolution cycle of smooth rational curves meeting transversely. Cusp singularities come in naturally dual pairs. Looijenga proved 1981 that if smoothable, the anticanonical divisor some surface. In 1983, second author and Miranda gave criterion for smoothability singularity, terms existence K-trivial semistable model central fiber such smoothing. We study these "Type III degenerations" surfaces with an divisor--their deformations, birational geometry, monodromy. Looijenga's original paper also description double point configurations to which deforms, but only case where has length 5 or less. generalize this classification arbitrary giving explicit construction simultaneous adjacency. The main tools proof are (1) formulas monodromy Type degeneration, (2) via surgeries on integral-affine degeneration prescribed monodromy, (3) surjectivity period map fibers, (4) theorem Shepherd-Barron producing contraction adjacency singularity.

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ژورنال

عنوان ژورنال: Journal of Differential Geometry

سال: 2021

ISSN: ['1945-743X', '0022-040X']

DOI: https://doi.org/10.4310/jdg/1620272941