p>
      The program reads a single input file, which contains a list
      that defines the 1D rules to be used as factors.
    </p>

    <p>
      Each 1D rule is stored in three files, an "X", "W", and "R" file,
      which are assumed to share a common filename prefix, so that
      the files defined by a given <i>prefix</i> have the form:
      <ul>
        <li>
          <i>prefix</i>_<b>x.txt</b>
        </li>
        <li>
          <i>prefix</i>_<b>w.txt</b>
        </li>
        <li>
          <i>p