Hawkes Process Classification through Discriminative Modeling of Text

Abstract

Social media such as Twitter has provided a platform for users to gather and share information and stay updated with the news. However, restriction on the length, informal grammar and vocabulary of the posts pose challenges to perform classification from textual content alone. We propose models based on the Hawkes process (HP) which can naturally incorporate additional cues such as the temporal features and past labels of the posts, along with the textual features for improving short text classification. In particular, we propose a discriminative approach to model text in HP, where the text features parameterize the base intensity and the triggering kernel of the intensity function. This allows textual content to determine influence from past posts and consequently determine the intensity function and class label. Another major contribution is to model the kernel as a neural network function of both time and text, permitting more complex influence functions for Hawkes process. This will maintain the interpretability of Hawkes process models along with the improved function learning capability of the neural networks. The proposed HP models can easily consider pretrained word embeddings to represent text for classification. Experiments on the rumour stance classification problems in social media demonstrate the effectiveness of the proposed HP models.