reserve fi,psi for Ordinal-Sequence,
  A,A1,B,C,D for Ordinal,
  X,Y for set,
  x,y for object;

theorem Th34:
  B*^A in C*^A implies B in C
proof
  assume that
A1: B*^A in C*^A and
A2: not B in C;
  C c= B by A2,ORDINAL1:16;
  hence contradiction by A1,ORDINAL1:5,ORDINAL2:41;
end;
