Improvements in the computation of ideal class groups of imaginary   quadratic number fields
  We investigate improvements to the algorithm for the computation of ideal class groups described by Jacobson in the imaginary quadratic case. These improvements rely on the large prime strategy and a new method for performing the linear algebra phase. We achieve a significant speed-up and are able to compute ideal class groups with discriminants of 110 decimal digits in less than a week. 
Jean-Fran\c{c}ois Biasse
math.NT cs.SC