The Generic Multiple-Precision Floating-Point Addition With Exact   Rounding (as in the MPFR Library)
  We study the multiple-precision addition of two positive floating-point numbers in base 2, with exact rounding, as specified in the MPFR library, i.e. where each number has its own precision. We show how the best possible complexity (up to a constant factor that depends on the implementation) can be obtain. 
Vincent Lef\`evre (INRIA Lorraine - LORIA)