theorem Th12:
  i <= j & ((Computation s).i)`1_3 = the AcceptS of T implies (
  Computation s).j = (Computation s).i
proof
  assume that
A1: i <= j and
A2: ((Computation s).i)`1_3 = the AcceptS of T;
  Following (Computation s).i = (Computation s).i by A2,Def6;
  hence thesis by A1,Th11;
end;
