Let be an elliptic curve over with supersingular reduction at and let be a false Tate extension of . On the one hand, I will explain how to define plus and minus Selmer groups of over using ideas from -adic Hodge theory, generalising works of Kobayashi. On the other hand, I will talk about some congruences of -values of which might give rise to a possible definition of plus and minus -adic -functions for , generalising works of Pollack.