Flipping surfaces

  title={Flipping surfaces},
  author={Paul Hacking and J. Tevelev and Giancarlo Urz'ua},
We study semistable extremal threefold neighborhoods following earlier work of Mori, Kollár, and Prokhorov. We classify possible flips and extend Mori’s algorithm for computing flips of extremal neighborhoods of type k2A to more general neighborhoods of type k1A. In fact we show that they belong to the same deformation family as k2A, and we explicitly construct the universal family of extremal neighborhoods. This construction follows very closely Mori’s division algorithm, which we interpret as… Expand

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