Parallel bundles in planar map geometries
  Parallel lines are very important objects in Euclid plane geometry and its behaviors can be gotten by one's intuition. But in a planar map geometry, a kind of the Smarandache geometries, the sutation is complex since it may contains elliptic or hyperbolic points. This paper concentrates on the behavior of parallel bundles, a generazation of parallel lines in plane geometry and obtains characteristics for for parallel bundles. 
Linfan Mao