Socially-Informed Timeline Generation for Complex Events

Human Language Technologies: The 2015 Annual Conference of the North American Chapter of the ACL, pages 1055–1065, Denver, Colorado, May 31 – June 5, 2015. c⃝2015 Association for Computational Linguistics Socially-Informed Timeline Generation for Complex Events Lu Wang Claire Cardie Galen Marchetti Department of Computer Science Cornell University Ithaca, NY 14853 {luwang, cardie}@cs.cornell.edu gjm97@cornell.edu Abstract Existing timeline generation systems for com- plex events consider only information from traditional media, ignoring the rich social con- text provided by user-generated content that reveals representative public interests or in- sightful opinions. We instead aim to gen- erate socially-informed timelines that con- tain both news article summaries and selected user comments. We present an optimization framework designed to balance topical cohe- sion between the article and comment sum- maries along with their informativeness and coverage of the event. Automatic evaluations on real-world datasets that cover four com- plex events show that our system produces more informative timelines than state-of-the- art systems. In human evaluation, the asso- ciated comment summaries are furthermore rated more insightful than editor’s picks and comments ranked highly by users. 1 Introduction Social media sites on the Internet provide increas- ingly more, and increasingly popular, means for people to voice their opinions on trending events. Traditional news media — the New York Times and CNN, for example — now provide online mecha- nisms that allow and encourage readers to share re- actions, opinions, and personal experiences relevant to a news story. For complex emerging events, in particular, user comments can provide relevant, in- teresting and insightful information beyond the facts reported in the news. But their large volume and tremendous variation in quality make it impossible * Comment A: The “Crimean Parliament”, headed by an ethnic Russian separatist who was elected leader of parliament AFTER pro-Russian armed forces occupied the parliamentary chambers, has voted for Crimea to be annexed into Russia… * Comment B: Does the West and US have a policy at all? The Obama administration has warned of “increasingly harsh sanctions”, but it is unlikely that Europe will comply… * Comment C: Sanctions are effective and if done in unison with the EU… - Crimeans vote in a referendum to rejoin Russia or return to its status under the 1992 constitution. March 16th, 2014 - The Crimean parliament officially declared independence and requested full accession to the Russian Federation. - Obama declared sanctions on Russian officials considered responsible for the crisis. - The leader of the pro-Russian organization “Youth Unity” was arrested. - President Obama warned Vladimir Putin that further provocations by Russia could isolate and diminish its influence. - One pro-Russian soldier was killed in the Simferopol incident. March 17th, 2014 March 18th, 2014 … summaries for other dates … Figure 1: A snippet of the event timeline on Ukraine Cri- sis is displayed on the left. On the right, we display a set of representative comments addressing the article sum- mary of March 17th. Comment A (underlined) brings a perspective on “Crimean parliament passes declaration of independence” …

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