</a>,
          the estimated positions of the chain letters, based on the distance table.
        </li>
      </ul>
    </p>

    <p>
      <b>GRID04</b> is a problem involving distances between pairs of 4 points.
      <ul>
        <li>
          <a href = "grid04_xy.txt">grid04_xy.txt</a>,
          positions of 4 points on a grid.
        </li>
        <li>
          <a href = "grid04_xy.png">grid04_xy.png</a>,
          an image of the 4 points on a grid.
        </li>
        <li>
          <a href = 