def METHOD_NAME(_X1, _Y1, _X2, _Y2):
    adist_m = proxy_a_distance(_X1, _X2)
    C = len(np.unique(_Y1))
    epsilon = 1e-3
    list_adist_c = []
    for i in range(1, C + 1):
        ind_i, ind_j = np.where(_Y1 == i), np.where(_Y2 == i)
        Xsi = _X1[ind_i[0], :]
        Xtj = _X2[ind_j[0], :]
        adist_i = proxy_a_distance(Xsi, Xtj)
        list_adist_c.append(adist_i)
    adist_c = sum(list_adist_c) / C
    mu = adist_c / (adist_c + adist_m)
    if mu > 1:
        mu = 1
    if mu < epsilon:
        mu = 0
    return mu