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Remarks on Type III Unprojection

Stavros Argyrios Papadakis
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Abstract

Type III unprojection plays a very important role in the birational geometry of Fano threefolds. It was first introduced by A. Corti on his calculations of Fano threefolds of genus 6 and 7. It seems that at present a general definition of the type III unprojection is still missing. After proving some general facts about residual ideals, we propose a definition for the generic Type III unprojection, and prove that it gives a Gorenstein ring.

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Stavros Argyrios Papadakis. 2005-01-29. Remarks on Type III Unprojection. https://arxiv.org/abs/math/0501535

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