Abstract
Suppose π: X → Y is a smooth blow-up along a submanifold Z of Y between complex Fano manifolds X and Y of pseudo-indices i X and i Y respectively (recall that i X is defined by i X :=min {−K X ·C | C is a rational curve of X}). We prove that \(i_X \leq i_Y\) if 2 dim (Z) < dim (Y)+i Y −1 and show that this result is optimal by classifying the ‘boundary’ cases. As expected, these results are obtained by studying rational curves on X and Y.
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Bonavero, L. Pseudo-Index of Fano Manifolds and Smooth Blow-Ups. Geom Dedicata 114, 79–86 (2005). https://doi.org/10.1007/s10711-004-1816-1
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DOI: https://doi.org/10.1007/s10711-004-1816-1