depend f,x,y;
write"f is ";
if freeof(f,y) then write"independent"
               else write"dependent";
write" of y."$
write"df(f,x) is ";
if freeof(df(f,x),y) then write"independent"
                     else write"dependent";
write" of y."$
write"int(f,x) is ";
if freeof(int(f,x),y) then write"independent"
                      else write"dependent";
write" of y."$
end;

