1.Triplet
https://www.jianshu.com/p/46c6f68264a1
http://lawlite.me/2018/10/16/Triplet-Loss%E5%8E%9F%E7%90%86%E5%8F%8A%E5%85%B6%E5%AE%9E%E7%8E%B0/
https://zhuanlan.zhihu.com/p/35560666
2、表示模型
https://zhuanlan.zhihu.com/p/27441587
3、MatchPyramid
https://blog.csdn.net/coraline_m/article/details/78796786
4、Rank
http://www.cnblogs.com/kemaswill/archive/2013/06/01/3109497.html
5、PQ(product quantization)