theorem
  for s being SCM-State of G, u being natural Number, mk being Element of
  SCM-Data-Loc holds SCM-Chg(s,u).mk = s.mk
proof
  let s be SCM-State of G, u be natural Number, mk be Element of SCM-Data-Loc;
  NAT in SCM-Memory by AMI_2:22;
  then SCM-OK.NAT = 0 & SCM-OK.mk = 1 by AMI_2:def 4;
  then not mk in dom(NAT .--> u) by TARSKI:def 1;
  hence thesis by FUNCT_4:11;
end;
