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Special effect varieties and (-1)-curves

Cristiano Bocci
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Abstract

Here we introduce the concept of special effect curve which permits to study, from a different point of view, special linear systems in P^2, i.e. linear system with general multiple base points whose effective dimension is strictly greater than the expected one. In particular we study two different kinds of special effect: the α-special effect is defined by requiring some numerical conditions, while the definition of h^1-special effect concerns cohomology groups. We state two new conjectures for the characterization of special linear systems and we prove they are equivalent to the Segre and the Harbourne-Hirschowitz ones.

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Cristiano Bocci. 2004-10-25. Special effect varieties and (-1)-curves. https://arxiv.org/abs/math/0410527

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