In Search of the Ur-Wikipedia: Universality, Similarity, and Translation in the Wikipedia Inter-language Link Network Morten Warncke-Wang1, Anuradha Uduwage1, Zhenhua Dong2, John Riedl1 1GroupLens Research Dept. of Computer Science and Engineering 2Dept. of Information Technical Science University of Minnesota Nankai University Minneapolis, Minnesota Tianjin, China {morten,uduwage,riedl}@cs.umn.edu [email protected] ABSTRACT 1. INTRODUCTION Wikipedia has become one of the primary encyclopaedic in- The world: seven seas separating seven continents, seven formation repositories on the World Wide Web. It started billion people in 193 nations. The world's knowledge: 283 in 2001 with a single edition in the English language and has Wikipedias totalling more than 20 million articles. Some since expanded to more than 20 million articles in 283 lan- of the content that is contained within these Wikipedias is guages. Criss-crossing between the Wikipedias is an inter- probably shared between them; for instance it is likely that language link network, connecting the articles of one edition they will all have an article about Wikipedia itself. This of Wikipedia to another. We describe characteristics of ar- leads us to ask whether there exists some ur-Wikipedia, a ticles covered by nearly all Wikipedias and those covered by set of universal knowledge that any human encyclopaedia only a single language edition, we use the network to under- will contain, regardless of language, culture, etc? With such stand how we can judge the similarity between Wikipedias a large number of Wikipedia editions, what can we learn based on concept coverage, and we investigate the flow of about the knowledge in the ur-Wikipedia? translation between a selection of the larger Wikipedias. Our findings indicate that the relationships between Wiki- pedia editions follow Tobler's first law of geography: sim- ilarity decreases with increasing distance. The number of Dutch articles in a Wikipedia edition is found to be the strongest Wikipedia predictor of similarity, while language similarity also appears to have an influence. The English Wikipedia edition is by 6 far the primary source of translations. We discuss the im- pact of these results for Wikipedia as well as user-generated 2 3 content communities in general. 1 5 7 Categories and Subject Descriptors 4 German French H.3.4 [Information Systems]: Systems and software|In- Wikipedia Wikipedia formation networks; H.5.3 [Information Systems]: Group and Organization Interfaces|computer-supported collabora- World knowledge tive work General Terms Figure 1: Illustration of shared and non-shared con- Human Factors, Measurement cepts in the world of knowledge between three of the largest Wikipedia editions. Keywords Shared concepts can be illustrated as shown in Figure 1, Wikipedia, Tobler's Law, First Law of Geography, Multilin- where we have simplified the case by using only three Wiki- gual pedia editions of approximately the same size. In this case there are seven numbered classes of concepts: the ones that are shared by all (1), those shared by two (2, 3, 4), and those Permission to make digital or hard copies of all or part of this work for unique to a specific edition (5, 6, 7). There is also a part of personal or classroom use is granted without fee provided that copies are world knowledge that is not covered by any Wikipedia, as not made or distributed for profit or commercial advantage and that copies Wikipedia content usually needs to meet a notability thresh- bear this notice and the full citation on the first page. To copy otherwise, to old and have verifiable sources. We are interested in un- republish, to post on servers or to redistribute to lists, requires prior specific derstanding what forces influence the number of concepts permission and/or a fee. WikiSym ’12, Aug 27-29, Linz, Austria in each of the numbered classes, expanded to encompass all Copyright 2012 ACM 978-1-4503-1605-7/12/08 ...$15.00. 283 Wikipedia editions. For instance it has been shown that location bias exists in some Wikipedias [6], and Dahinden [4] coverage of the article \Game" in four Wikipedias and found found a connection between where a language is used and correlation with some of Hofstede's dimensions of cultural the location of articles in the same Wikipedia language edi- influence. Callahan and Herring [3] analysed coverage of tion. If it is possible to locate certain Wikipedia editions to famous persons in the English and Polish Wikipedias and specific geographic regions we might therefore be able to de- discovered systematic differences but no indication of inten- cide what influence geographic distance between Wikipedias tional bias. Yasseri et al. [32] used regularity in the edit has on the similarity between them. patterns of the larger Wikipedia editions to estimate the geo- Articles about the same concept have been linked across graphical distribution of their editors. Adar et al. [1] studied the different language Wikipedias from the early days. The tables with summary information about a topic, called in- inter-language link (ILL) network contains as of early Jan- foboxes, mining data from the English, German, French and uary 2012 more than 224 million links between the more Spanish Wikipedias to show that the information could to than 20 million articles. It is a decentralised system where a large extent be discovered and consolidated automatically each article is responsible for linking to all other languages through machine learning. The featured article approval where the same article exists1. Originally this network was process of Arabic, English, and Korean Wikipedias was ex- maintained manually, now Wikipedia users have a collec- plored by Stvilia et al. [23], finding that both their quality tion of software robots called interwiki bots to help them. models and understanding of quality differed. Hecht and The bots follow the ILLs to decide which languages have Gergle [7] studied 25 of the largest Wikipedia editions and an article in order to add, update, or remove links as nec- found strong evidence against there being a global consen- essary. Because they use only the ILLs they are unable to sus of world knowledge. In this paper we extend the exist- discover isolated articles that should be linked, and the num- ing literature by exploring metrics to quantify the similarity ber of missing links varies between editions [7]. Research between Wikipedia editions, and by using these metrics to on the existing network has identified errors from incorrect identify what factors affect similarity. links [5], from differences when deciding how to cover certain Much of the existing research has used a single language topics [7], and because the boundaries of concepts vary [2]. edition as a data source, English Wikipedia in particular. It is not difficult to find anecdotal evidence to show that Some of the issues that have been explored are: how users there are differences in content coverage of the same con- work together [29, 30, 13, 25], how article quality devel- cept. For example the English edition's article about the ops [31, 24, 15], and how different users contribute vastly Norwegian politician Erik Solheim2 contains several para- different amounts of content to the encyclopaedia [18, 11]. graphs about his work in the Sri Lankan peace negotiation There are also examples of research using other Wikipedias process, including a section on controversies about alleged as a source, such as Stein and Hess [22] who looked into bias towards one side of the conflict, while the Norwegian how certain contributors greatly affected article quality in edition's article3 contains only a single three-sentence para- the German edition. graph and completely omits the Sri Lankan point of view. Researchers have also looked at other networks. Roth et There are two official languages in Sri Lanka: Sinhala and al. [20] mined data from about 360 different wikis to un- Tamil. The Sinhala Wikipedia edition contains as of March derstand how macroscopic indicators, structural features, 2012 about 6,000 articles, but does not have an article about and governance policies affect growth patterns, while Kit- Erik Solheim. Tamil Wikipedia has more than 43,000 arti- tur and Kraut [12] sampled 6,118 wiki production groups cles, and the one about Erik Solheim4 lists only the basic to understand how a selection of coordination mechanisms facts about him and that he was involved in the peace talks affect task quality and conflict in systems that are similar to from 2000 to 2006. Wikipedia. On the popular social networking site Twitter, There are also similarities and differences among Wiki- Hong et al. [10] discovered that across languages users differ pedia editions as a whole. In the book \The Wikipedia Rev- in their inclusion of URLs in tweets, as well as Twitter- olution" [16], Lih mentions the story of how contributors to specific features like hashtags, mentions, and retweets. A the Spanish edition branched out and created Enciclopedia paper on the blogging site LiveJournal has also shown that Libre in 2002 after disputes about financing Wikipedia with there existed at least four distinct networks of users writ- advertisements, leaving Spanish Wikipedia nearly inactive ing blog entries in languages other than English: Russian, for a year and a half. The book also mentions that Japanese Portuguese, Finnish, and Japanese [9]. Wikipedia has a much larger proportion of users who do not create an account (so called \anonymous users") compared 2. RESEARCH QUESTIONS to other Wikipedias of similar size. The existing literature raises a number of fascinating ques- Research has also emerged describing similarities and dif- tions about information flow across languages and cultures, ferences between Wikipedias. Pfeil et al. [17] looked at the with the ILLs in Wikipedia providing a rich source of data about those questions.