theorem
  (a,k1)>=0_goto k2 is non halting
proof
  consider s being State of SCMPDS such that
A1: for d being Int_position holds s.d = -1 by Th57;
  s.DataLoc(s.a,k1) = -1 by A1;
  then Exec((a,k1)>=0_goto k2, s).IC SCMPDS = IC s + 1 by Th54;
  hence thesis by Th60;
end;
