private boolean solveEnvHasOneUnknownCardInGroup(int l, int r)
                                                throws ContradictionException {
        boolean tableModified = false;
        int minuses = 0;
        for (int i = l; i < r; ++i) {
            if (table[i][ENV_COL] == Resolution.Minus) {
                ++minuses;
            }
        }
        if (minuses == (r - l - 1)) {
            for (int i = l; i < r; ++i) {
                if (table[i][ENV_COL] != Resolution.Minus) {
                    boolean setPlusValue = setPlus(i, ENV_COL);
                    tableModified = tableModified || setPlusValue;
                }
            }
        }
        return tableModified;
    }