Bjorn Poonen  (MIT)
Existence of rational points on smooth projective varieties
Let k be a number field.  We prove results including:
  
1) If there is an algorithm to decide whether a smooth projective
   k-variety has a k-point, then there is an algorithm to decide
   whether an arbitrary k-variety has a k-point.
2) If there is an algorithm to decide whether a smooth projective
   3-fold has a k-point, then there is an algorithm to compute X(k)
   for any curve X over k.