“…Additionally, unsupervised techniques such as language modeling (Allan et al, 2001) have been used for temporal summarization. In recent years, ranking and graph-based methods (Radev et al, 2004b;Erkan and Radev, 2004;Mihalcea and Tarau, 2004;Fader et al, 2007;Hassan et al, 2008;Mei et al, 2010;Yan et al, 2011b;Yan et al, 2011a;Zhao et al, 2013;Ng et al, 2014;Zhou et al, 2014;Glavaš andŠnajder, 2014;Tran et al, 2015;Dehghani and Asadpour, 2015) have also proved popular for extractive timeline summarization, often in an unsupervised setting. Dynamic programming (Kiernan and Terzi, 2009) and greedy algorithms (Althoff et al, 2015) have also been considered for constructing summaries over time.…”