Thurston's remaining challenge:
Show that volumes of hyperbolic 3-manifolds are not all rationally related.
THURSTON'S VISION AND THE VIRTUAL FIBERING THEOREMTHURSTON'S VISION AND THE VIRTUAL FIBERING THEOREM
Is there an algorithm which determines whether two funda- mental groups of 3-manifolds are isomorphic?
DECISION PROBLEMS FOR 3-MANIFOLDS AND THEIR FUNDAMENTAL GROUPS