Xu Sun Takuya Matsuzaki Daisuke Okanohara Jun-ichi Tsujii Latent Variable Perceptron Algorithm for Structured Classification. 1236-1242 2009 IJCAI http://ijcai.org/papers09/Papers/IJCAI09-208.pdf conf/ijcai/2009 db/conf/ijcai/ijcai2009.html#SunMOT09