code>
                  </p>
                </td>
<td>
                  <p>
                    <code class="computeroutput"><span class="identifier">X</span><span class="special">&amp;</span></code>
                  </p>
                </td>
<td>
                  <p>
                    pre: there exists <code class="computeroutput"><span class="identifier">s</span></code>
                    such that <code class="computeroutput"><span class="identifier">r</span> <span class="special">==</span> <span