Morphisms between elliptic curves. The group law. Arithmetic of elliptic curves (a glimpse: Mordell’s theorem, L-functions, the Birch and Swinnerton-Dyer conjecture).
The group SL(2,Z). The space of all lattices. The trefoil knot.
Modular forms for SL(2,Z): finite-dimensionality. Eisenstein series.
Theta series. Four squares. Even unimodular lattices and sphere packing in dimension 8.
Hecke operators. `Reminders’ on the Riemann zeta function. L-functions. Modularity of elliptic curves (statement).
The Ramanujan conjecture. Expander graphs. The j-invariant. Moonshine.