Comparison of Fundamental Group Schemes of a Projective Variety and an Ample Hypersurface
نویسنده
چکیده
Let X be a smooth projective variety defined over an algebraically closed field, and let L be an ample line bundle over X . We prove that for any smooth hypersurface D on X in the complete linear system |L|, the inclusion map D →֒ X induces an isomorphism of fundamental group schemes, provided d is sufficiently large and dimX ≥ 3. If dimX = 2, and d is sufficiently large, then the induced homomorphism of fundamental group schemes remains surjective. We give an example to show that the homomorphism of fundamental group schemes induced by the inclusion map of a reduced ample curve in a smooth projective surface is not surjective in general.
منابع مشابه
Normal generation of very ample line bundles on toric varieties ∗
Let A and B be very ample line bundles on a projective toric variety. Then, it is proved that the multiplication map Γ(A)⊗ Γ(B) → Γ(A⊗B) of global sections of the two bundles is surjective. As a consequence, it is showed that any very ample line bundle on a projective toric variety is normally generated. As an application we show that any ample line bundle on a toric Calabi-Yau hypersurface is ...
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