private double propb(Word wl, Word wr) {
		double sumB = 0.0;
		long freq_lr = 0l, freq_r = 0l, ln = 0l;
		if (wl != null && wr != null) {
			Long val = wl.r_relate.getVal(wr.id);
			freq_lr = (val != null ? val : 0l);
		}
		if (wl != null) {
			sumB = wl.weight;
			freq_r = wl.freq();
		}
		if (wr != null) {
			ln = wr.l_diff;
		}
		if (freq_r > 0l) {
			return (freq_lr - D(freq_lr) + sumB * ln / ww_diff) / freq_r;
		}
		return 0.0;
	}