Shyi-Chyi Cheng Ming-Yao Chen Hong-Yi Chang Tzu-Chuan Chou Semantic-based facial expression recognition using analytical hierarchy process. 86-95 2007 33 Expert Syst. Appl. 1 http://dx.doi.org/10.1016/j.eswa.2006.04.019 db/journals/eswa/eswa33.html#ChengCCC07