protected Element createCaseElement(Document doc, Case c) {
    Element elem = createElement(doc, CASE_NAME, null, null);

    int[] decomposition = c.getInput();
    elem.appendChild(createElement(doc, CASE_U_NAME, null, "" + decomposition[0]));
    elem.appendChild(createElement(doc, CASE_V_NAME, null, "" + decomposition[1]));
    elem.appendChild(createElement(doc, CASE_X_NAME, null, "" + decomposition[2]));
    elem.appendChild(createElement(doc, CASE_Y_NAME, null, "" + decomposition[3]));
    elem.appendChild(createElement(doc, CASE_I_NAME, null, "" + c.getI()));
    return elem;
  }