Fine Grained Citation Span for References in Wikipedia

Proceedings of the 2017 Conference on Empirical Methods in Natural Language Processing, pages 1990–1999 Copenhagen, Denmark, September 7–11, 2017. c⃝2017 Association for Computational Linguistics Fine-Grained Citation Span Detection for References in Wikipedia Besnik Fetahu1, Katja Markert2 and Avishek Anand1 1 L3S Research Center, Leibniz University of Hannover Hannover, Germany {fetahu, anand}@L3S.de 2 Institute of Computational Linguistics, Heidelberg University Heidelberg, Germany markert@cl.uni-heidelberg.de Abstract Verifiability is one of the core editing prin- ciples in Wikipedia, editors being encour- aged to provide citations for the added content. For a Wikipedia article, determin- ing the citation span of a citation, i.e. what content is covered by a citation, is impor- tant as it helps decide for which content citations are still missing. We are the first to address the problem of determining the citation span in Wikipedia articles. We approach this problem by classifying which textual fragments in an article are covered by a citation. We pro- pose a sequence classification approach where for a paragraph and a citation, we determine the citation span at a fine- grained level. We provide a thorough experimental eval- uation and compare our approach against baselines adopted from the scientific do- main, where we show improvement for all evaluation metrics. 1 Introduction Citations uphold the crucial policy of verifiability in Wikipedia. This policy requires Wikipedia con- tributors to support their additions with citations from authoritative external sources (web, news, journal etc.). In particular, it states that “arti- cles should be based on reliable, third-party, pub- lished sources with a reputation for fact-checking and accuracy”1. Not only are citations essential in maintaining reliability, neutrality and authori- tative assessment of content in such a collabora- tively edited platform; but lack of citations are 1https://en.wikipedia.org/wiki/ Wikipedia:Identifying_reliable_sources At the summit of the climb, carpet tacks[1] were thrown onto the road causing as many as thirty riders to puncture,[2][3] including Gilbert's team- mates Cadel Evans and Steve Cummings,[39] while race leader Bradley Wiggins […] precaution.[42] As a result, […] and eventually soloed his way to a fourth career stage victory at the Tour.[47] Sagan led home a group of four riders almost a minute behind, […] behind Sánchez.[39] Figure 1: Sub-sentence level span for citation [1] in a citing paragraph in a Wikipedia article. essential signals for core editors for unreliability checks. However, there are two problems when it comes to citing facts in Wikipedia. First, there is a long tail of Wikipedia pages where citations are missing and hence facts might be unverified. Second, cita- tions might have different span granularities, i.e., the text encoding the fact(s), for which a citation is intended, might span less than a sentence (see Fig- ure 1) to multiple sentences. We denote the differ- ent pieces of text which contain a citation marker as fact statements or simply statements. For exam- ple, Table 1 shows different statements for several citations. The aim of this work is to automatically and accurately determine citation spans in order to improve coverage (Fetahu et al., 2015b, 2016) and to assist …

Content truncated to 500 words