On the integral $2$-adic Tate module of elliptic curves
We show that the integral $2$-adic Tate module of an elliptic curve over a complete discretely valued field of odd residue characteristic is determined by its $2$-torsion representation, together with the square class of $c$ and local information about the pairwise differences of the roots of $f$ in a model $E\colon y^...