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 Th65:
  for f,g being Function, x,y being object st [x,y] in [:dom f,dom g:]
  holds [:f,g:].(x,y) = [f.x,g.y]
proof
  let f,g be Function, x,y be object;
  assume [x,y] in [:dom f,dom g:];
  then x in dom f & y in dom g by ZFMISC_1:87;
  hence thesis by Def8;
end;
