On turbulent relations
  This paper extends the theory of turbulence of Hjorth to certain classes of equivalence relations that cannot be induced by Polish actions. It applies this theory to analyze the quasi-isometry relation and finite Gromov-Hausdorff distance relation in the space of isometry classes of pointed proper metric spaces, called the Gromov space. 
Jes\'us A. \'Alvarez L\'opez and Alberto Candel
math.LO math.DS math.MG