The sum of the interior angles in geodesic and translation triangles of   Sl2(R) geometry
  We study the interior angle sums of translation and geodesic triangles in the universal cover of Sl2(R) geometry. We prove that the angle sum is larger then pi for translation triangles and for geodesic triangles the angle sum can be larger, equal or lessthan \pi. 
G\'eza Csima, Jen\H{o} Szirmai
math.MG