On the extendability of elliptic surfaces of rank two and higher
On the extendability of elliptic surfaces of rank two and higher
We study threefolds X⊂ℙ r having as hyperplane section a smooth surface with an elliptic fibration. We first give a general theorem about the possible embeddings of such surfaces with Picard number two. More precise results are then proved for Weierstrass fibrations, both of rank two and higher. In particular …