## Remarks on Gorenstein Terminal Fourfold Flips

J. Math. Sci. Univ. Tokyo
Vol. 5 (1998), No. 1, Page 149--164.

Takagi, Hiromichi
Remarks on Gorenstein Terminal Fourfold Flips
We prove that for any flipping contraction from a Gorenstein terminal $4$-fold, a general hyperplane section which contains the exceptional locus has only canonical singularities. Based on this fact and using Ran's theorem, we prove the existence of the flip of a flipping contraction from a Gorenstein terminal $4$-fold whose general hyperplane section has only isolated canonical singularities and exceptional locus is irreducible. Furthermore we classify such flipping contractions and flips.