Compatibility of distortion fields caused by topological defects in 2D   latties
  Topological defects in crystalline lattices are considered. In relation to physical realizability of such defects, criteria for geometric compatibility of the lattice distortions are formulated. For 2D lattices it is shown that the answer to the question of existence of distortion fields which are both geometrically compatible and homotopically non-trivial is in the affirmative. 
Dominik Rogula (Warsaw)