L-functions with Large Analytic Rank and Abelian Varieties with Large Algebraic Rank over Function Fields

The goal of this paper is to explain how a simple but apparently new fact of linear algebra together with the cohomological interpretation of L-functions allows one to produce many examples of L-functions over function fields vanishing to high order at the center point of their functional equation. Conjectures of Birch and Swinnerton-Dyer, Bloch, and Beilinson relate the orders of vanishing of some of these L-functions to Mordell-Weil groups and other groups of algebraic cycles. For certain abelian varieties of high analytic rank, we are also able to prove the conjecture of Birch and Swinnerton-Dyer thus establishing the existence of large Mordell-Weil groups in those cases. In the rest of this section we state the main results of the paper.