theorem Th14:
  (maxfuncreal(A)).((minfuncreal(A)).(g,f),f)=f
proof
  thus (maxfuncreal(A)).((minfuncreal(A)).(g,f),f) =(maxfuncreal(A)).((
  minfuncreal(A)).(f,g),f) by Th9
    .=f by Th13;
end;
