I. Introduction
In supervised learning, most of the research concentrated on data where each example is labelled with only one label, known as single-label data. But in many real life applications, examples are associated with a subset of labels unlike single-label data. This setting, where examples are tagged with a set of labels, is known as multi-label data. Binary classification and multi-class classification are special cases of single-label classification. If the label set L contains only two elements (i. e| L | = 2) then single-label classification becomes binary classification. Otherwise (i.e.,| L |> 2), it becomes multi-class classification.