sentences:  Then there is a spectral sequence of cohomological type
  
  and there is a spectral sequence of homological type
  
  The same statement holds if "G" is a profinite group, "N" is a "closed" normal subgroup and "H*" denotes the continuous cohomology.The spectral sequence can be used to compute the homology of the Heisenberg group "G" with integral entries, i.e., matrices of the form
  
  This group is a central extension
  
  with center formula_5 corresponding to the subgroup with "a"="c"=0.The spectral sequence for the group homology, together with the analysis of a differential in this spectral sequence, shows that
  
  For a group "G", the wreath product is an extension
  
  The resulting spectral sequence of group cohomology with coefficients in a field "k",
  
  is known to degenerate at the formula_9-page.