Minimal area ellipses in the hyperbolic plane
  We present uniqueness results for enclosing ellipses of minimal area in the hyperbolic plane. Uniqueness can be guaranteed if the minimizers are sought among all ellipses with prescribed axes or center. In the general case, we present a sufficient and easily verifiable criterion on the enclosed set that ensures uniqueness. 
Matthias J. Weber, Hans-Peter Schr\"ocker
math.MG