Stacking Label Features for Learning Multilabel Rules

Dependencies between the labels is commonly regarded as the crucial issue in multilabel classification. Rules provide a natural way for symbolically describing such relationships, for instance, rules with label tests in the body allow for representing directed dependencies like implications, subsumptions, or exclusions. Moreover, rules naturally allow to jointly capture both local and global label dependencies. We present a bootstrapped stacking approach which uses a common rule learner in order to induce label-dependent rules. For this, we learn for each label a separate ruleset, but we include the remaining labels as additional attributes in the training instances. Proceeding this way, label dependencies can be made explicit in the rules. Our experiments show competitive results in terms of the standard multilabel evaluation measures. But more importantly, using these additional attributes is shown to allow to discover and consider label relations as well as to better comprehend the available multilabel datasets. However, this approach is only a first step towards integrating the multilabel rule learning directly in the rule induction process, e.g., in typical separate-andconquer rule learners. We present future perspectives, advantages, and arising issues in this regard.