The support problem for abelian varieties
  Let $A$ be an abelian variety over a number field $K$. If $P$ and $Q$ are $K$-rational points of $A$ such that the order of the reduction of $Q$ divides that of $P$ for all but finitely many primes of the ring of integers of $K$, then there exists a $K$-endomorphism $\phi$ of $A$ and a positive integer $k$ such that $kQ = \phi(P)$. 
Michael Larsen