Classification of extremal contractions from smooth fourfolds of (3,1)-type

Takagi, Hiromichi

doi:10.1090/S0002-9939-99-05114-X

Classification of extremal contractions from smooth fourfolds of (3,1)-type
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Proc. Amer. Math. Soc. 127 (1999), 315-321 Request permission

Abstract:

We investigate divisorial contractions of extremal rays from smooth fourfolds. When the exceptional divisor is contracted to a curve, we prove that the divisor is a $\mathbb {P}^{2}$-bundle or quadric bundle over a smooth curve and the contraction is the blowing up along the curve. Furthermore we determine the local analytic structure of the contraction.

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