(%o4)      [f(x), g(x), r(u, v, w), s(u, v, w), u(t)]
(%i5) diff (r.s, u);
                         dr           ds
(%o5)                    -- . s + r . --
                         du           du
</pre>
<pre class="example">(%i6) diff (r.s, t);
                      dr du           ds du
(%o6)                 -- -- . s + r . -- --
                      du dt           du dt
</pre>
<pre class="example">(%i7) remove (r, dependency);
(%o7)                         done
(%i8) diff (r.s, t);
                   