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.