We propose a new approach for extracting argument structure from natural language texts that contain an underlying argument. Our approach comprises of two phases: Score Assignment and Structure Prediction. The Score Assignment phase trains models to classify relations between argument units (Support, Attack or Neutral). To that end, different training strategies have been explored. We identify different linguistic and lexical features for training the classifiers. Through ablation study, we observe that our novel use of word-embedding features is most effective for this task. The Structure Prediction phase makes use of the scores from the Score Assignment phase to arrive at the optimal structure. We perform experiments on three argumentation datasets, namely, AraucariaDB, Debatepedia and Wikipedia. We also propose two baselines and observe that the proposed approach outperforms baseline systems for the final task of Structure Prediction.

The paper presents a new fuzzy agreement measure $\gamma_f$ for determining the agreement in multi-label and subjective annotation task. In this annotation framework, one data item may belong to a category or a class with a belief value denoting the degree of confidence of an annotator in assigning the data item to that category. We have provided a notion of disagreement based on the belief values provided by the annotators with respect to a category. The fuzzy agreement measure $\gamma_f$ has been proposed by defining different fuzzy agreement sets based on the distribution of difference of belief values provided by the annotators. The fuzzy agreement has been computed by studying the average agreement over all the data items and annotators. Finally, we elaborate on the computation $\gamma_f$ measure with a case study on emotion text data where a data item (sentence) may belong to more than one emotion category with varying belief values.