Abstract:
As was made famous by Mazur, the mod-5 Galois
representation associated to the elliptic curve
is reducible. In fact, the mod-25 Galois
representation is also reducible. We will talk about
this kind of extra reducibility phenomenon, and how
its related, on one hand, to a ‘tame deriviative’ of
an L-function, and on the other hand, to an
algebraic invariant. This type of relation is
predicted by the Bloch-Kato conjecture. This is a
joint work with Akshay Venkatesh.