“…In the former, the problem is to distinguish between two classes, while in the latter there are more than two classes. The multi-class classification problem is considerably more complex because a decision boundary needs to be established to distinguish among many classes [15]. Multi-class classification tasks are widely used in many real-world applications, such as sentiment classification [2,6,31,42], fault diagnosis [28,34], and medical treatment [5,32,36].…”