Unsupervised approaches (Wang and Oard, 2009) estimate the relationship between messages through unsupervised similarity functions such cosine similarity, and assign messages to conversations based on a predefined threshold.
supervised methods exploit a set of user annotations (Elsner and Charniak, 2008;Mayfield et al., 2012;Shen et al., 2006;Du et al., 2017;Mehri and Carenini, 2017) to adapt to different datasets.