Supersingular reduction of an elliptic curve
= Supersingular reduction of an elliptic curve
= Supersingular reduction
{synonym}
A good reduction in characteristic $p$ is supersingular when its geometric $p$-torsion is trivial, equivalently its <formal group of an elliptic curve> has height two. Good inert primes of a <CM elliptic curve> are supersingular. The ordinary bounded-measure and torsion-Selmer formulation must then be modified, for instance using signed local conditions in the cyclotomic tower.