theorem Th60:
  for I being Instruction of SCMPDS st ex s st Exec(I,s).IC SCMPDS
  = IC s + 1 holds I is non halting
proof
  let I be Instruction of SCMPDS;
  given s such that
A1: Exec(I, s).IC SCMPDS = IC s + 1;
  assume I is halting;
  then Exec(I,s).IC SCMPDS = s.NAT by Th1;
  hence contradiction by A1,Th1;
  IC s = s.NAT by AMI_2:22,SUBSET_1:def 8;
  then reconsider w = s.NAT as Element of NAT;
end;
