Analyzing Topic Transitions in Text-Based Social Cascades Using Dual-Network Hawkes Process Jayesh Choudhari 1(B ) , Srikanta Bedathur 2 , Indrajit Bhattacharya 3 , and Anirban Dasgupta 4 1 University of Warwick, Coventry, UK choudhari.jayesh@alumni.iitgn.ac.in 2 Indian Institute of Technology Delhi, New Delhi, India srikanta@cse.iitd.ac.in 3 TCS Research, Kolkata, India b.indrajit@tcs.com 4 Indian Institute of Technology Gandhinagar, Ahmedabad, India anirbandg@iitgn.ac.in Abstract. We address the problem of modeling bursty diffusion of text- based events over a social network of user nodes. The purpose is to recover, disentangle and analyze overlapping social conversations from the perspective of user-topic preferences, user-user connection strengths and, importantly, topic transitions. For this, we propose a Dual-Network Hawkes Process (DNHP), which executes over a graph whose nodes are user-topic pairs, and closeness of nodes is captured using topic-topic, a user-user, and user-topic interactions. No existing Hawkes Process model captures such multiple interactions simultaneously. Additionally, unlike existing Hawkes Process based models, where event times are generated first, and event topics are conditioned on the event times, the DNHP is more faithful to the underlying social process by making the event times depend on interacting (user, topic) pairs. We develop a Gibbs sampling algorithm for estimating the three network parameters that allows evidence to flow between the parameter spaces. Using experiments over large real collection of tweets by US politicians, we show that the DNHP generalizes better than state of the art models, and also provides interesting insights about user and topic transitions. Keywords: Network Hawkes process · Generative models · Gibbs sampling This project has received funding from the Engineering and Physical Sciences Research Council, UK (EPSRC) under Grant Ref: EP/S03353X/1, CISCO University grant, and Google India AI-ML award. Electronic supplementary material The online version of this chapter (https:// doi.org/10.1007/978-3-030-75762-5 25) contains supplementary material, which is available to authorized users. c  Springer Nature Switzerland AG 2021 K. Karlapalem et al. (Eds.): PAKDD 2021, LNAI 12712, pp. 305–319, 2021. https://doi.org/10.1007/978-3-030-75762-5_25