theorem Th17:
  for Gc, Hc being strict finite cyclic Group st card Hc = card Gc
  holds Hc,Gc are_isomorphic
proof
  let Gc, Hc be strict finite cyclic Group;
  set p = card Hc;
  assume card Hc = card Gc;
  then
A1: INT.Group(p),Gc are_isomorphic by Th15;
  INT.Group(p),Hc are_isomorphic by Th15;
  hence thesis by A1,GROUP_6:67;
end;
