puteroutput"><span class="identifier">Y</span></code>.
            </p></dd>
<dt><span class="term">(b) Y-&gt;X:</span></dt>
<dd><p>
              <code class="computeroutput"><span class="identifier">R</span><span class="special">(</span><span class="identifier">Y</span><span class="special">)</span> <span class="special">&amp;</span> <span class="identifier">R</span><span class="special">(</span><span class="identifier">X</span><span class="special">)</span> <span class="special">==</span> <span class="id