theorem
  for s being SCM-State of G, u, v being natural Number
  holds SCM-Chg(s,u).v = s.v
proof
  let s be SCM-State of G, u, v be natural Number;
  not v in dom(NAT .--> u) by TARSKI:def 1;
  hence thesis by FUNCT_4:11;
end;
