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;
