theorem
  M is strongly_inaccessible implies Rank M is being_a_model_of_ZF
proof
  assume M is strongly_inaccessible;
  then
A1: Rank M is Universe by CARD_LAR:38;
  omega c= M;
  then omega c< M;
  then
A2: omega in M by ORDINAL1:11;
  M c= Rank M by CLASSES1:38;
  hence thesis by A1,A2,Th6;
end;
