“…Reinforcement learning [Mnih, Kavukcuoglu, Silver et al (2015)] emphasizes how to act on the environment to maximize the expected benefits. In application, deep learning has been greatly developed in the fields of video [Feichtenhofer, Fan, Malik et al (2018); Wichers, Villegas, Erhan et al (2018); Wang, Liu, Zhu et al (2018)], image [Xie, He, Zhang et al (2018); Barz and Denzler (2018); Wang and Chan (2018)], voice [Yang, Lalitha, Lee et al (2018); Arik, Chen, Peng et al (2018); Qian, Du, Hou et al (2017)], semantic understanding [Qin, Kamnitsas, Ancha et al (2018); Zhuang and Yang (2018); Sanh, Wolf and Ruder (2018)], and has been further applied in object detection [Roddick, Kendall and Cipolla (2018) ;Jaeger, Kohl, Bickelhaupt et al (2018)], image forensics [Yu, Zhan and Yang (2016), Cui, McIntosh and Sun (2018)], intelligent management [Liang, Jiang, Chen et al (2018); Le, Pham, Sahoo et al (2018); Duan, Lou, Wang et al (2017)] and medicine [Mobadersany, Yousefi, Amgad et al (2018); Rajpurkar, Irvin, Zhu et al (2017); Akkus, Galimzianova, Hoogi et al (2017)]. In the field of supervised learning, image classification methods that based on deep learning have been mature, which can be applied to object detection and image retrieval.…”