Five methods for multi-class classification are introduced based on widely used SVMs. They are one versus rest(OVR),one versus one(OVO),binary tree(BT),error correcting output codes(ECOC) and directed acyclic graph(DAG).

• 当前针对多类问题的支持向量机分类方法主要有5种:一类对余类法(OVR),一对一法(OVO),二叉树法(BT),纠错输出编码法和有向非循环图法。