def AchillesHeel(*xs, simplify=True):
    r"""
    Return the Achille's Heel function, defined as:
    :math:`\prod_{i=0}^{n/2-1}{X_{2i} + X_{2i+1}}`.

    If *simplify* is ``True``, return a simplified expression.
    """
    nargs = len(xs)
    if nargs & 1:
        fstr = "expected an even number of arguments, got {}"
        raise ValueError(fstr.format(nargs))
    xs = [Expression.box(x).node for x in xs]
    y = exprnode.and_(*[exprnode.or_(xs[2*i], xs[2*i+1])
                        for i in range(nargs // 2)])
    if simplify:
        y = y.simplify()
    return _expr(y)