reserve p,q,x,x1,x2,y,y1,y2,z,z1,z2 for set;
reserve A,B,V,X,X1,X2,Y,Y1,Y2,Z for set;
reserve C,C1,C2,D,D1,D2 for non empty set;

theorem
  for f1 being Function of X1,D1 for f2 being Function of X2,D2 holds [:
  f1,f2:] = <:f1*pr1(X1,X2),f2*pr2(X1,X2):>
proof
  let f1 be Function of X1,D1;
  let f2 be Function of X2,D2;
  dom f1 = X1 & dom f2 = X2 by FUNCT_2:def 1;
  hence thesis by Th66;
end;
