hcibib10: {hypertext,hypermedia} : Human-Computer Interaction Bibliography Search

HYPER10 = ^ + EN RW = EN RW CONFERENCE PROCEEDINGS Hypertext'10: Proceedings of the 21st ACM Conference on Hypertext and Hypermedia / Mark Chignell Elaine Toms Toronto, Canada 2010-06-29 2010-07-01 2010 ACM n.59 p.318 ISBN: 1-4503-0041-3, 978-1-4503-0041-4

Keynote (1)
Information searching (4)
Recommenders (4)
Adaptation (4)
Algorithms and methods (3)
Networked communities (4)
Tagging (4)
Frontiers (3)
Panel (1)
ELearning and navigation (3)
Discussion paper (1)
User models (3)
Poster session (19)
Demo session (3)
Panel: visions of hypertext (1)
Closing keynote address (1)

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= ^ + EN RW G A study of tabbed browsing among Mozilla Firefox users Browsing / Dubroy, Patrick / Balakrishnan, Ravin Proceedings of ACM CHI 2010 Conference on Human Factors in Computing Systems 2010 v.1 p.673-682

Keywords: hypertext, tabbed document interfaces, tabs, web browser interfaces, web browsing, www

doi.acm.org/10.1145/1753326.1753426 ACM Digital Library

Summary: We present a study which investigated how and why users of Mozilla Firefox use multiple tabs and windows during web browsing. The detailed web browsing usage of 21 participants was logged over a period of 13 to 21 days each, and was supplemented by qualitative data from diary entries and interviews. Through an examination of several measures of their tab usage, we show that our participants had a strong preference for the use of tabs rather than multiple windows. We report the reasons they cited for using tabs, and the advantages over multiple windows. We identify several common tab usage patterns which browsers could explicitly support. Finally, we look at how tab usage affects web page revisitation. Most of our participants switched tabs more often than they used the back button, making tab switching the second most important navigation mechanism in the browser, after link clicking.

= ^ + EN RW G Navigational complexity in web interactions WWW posters / Chandra, Praphul / Manjunath, Geetha Proceedings of the 2010 International Conference on the World Wide Web 2010 v.1 p.1075-1076

Keywords: complexity, graph theory, hypertext, user interaction, widgets

doi.acm.org/10.1145/1772690.1772811 ACM Digital Library

Summary: As the web grows in size, interfaces & interactions across websites diverge -- for differentiation and arguably for a better user experience. However, this size & diversity is also a cognitive load for the user who has to learn a new user interface for every new website she visits. Several studies have confirmed the importance of well designed websites. In this paper, we propose a method for quantitative evaluation of the navigational complexity of user interactions on the web. Our approach of quantifying interaction complexity exploits the modeling of the web as a graph and uses the information theoretic definition of complexity. It enables us to measure the navigational complexity of web interaction in bits. Our approach is structural in nature and can be applied to both traditional paradigm of web interaction (browsing) and to emerging paradigms of web interaction like web widgets.

= ^ + EN RW G As we may have thought, and may (still) think Keynote / Dillon, Andrew Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.1-2

Keywords: e-books, human factors

doi.acm.org/10.1145/1810617.1810619 ACM Digital Library

Summary: The promise of electronic documents is long lived yet curiously uninspiring in execution. In this address I will revisit the promises and consider the progress and problems faced over the last two decades in creating the information spaces imagined by the field's founders.

= ^ + EN RW G Is this a good title? Information searching / Klein, Martin / Shipman, Jeffery / Nelson, Michael L. Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.3-12

Keywords: digital preservation, web page discovery, web page titles

doi.acm.org/10.1145/1810617.1810621 ACM Digital Library

Summary: Missing web pages, URIs that return the 404 "Page Not Found" error or the HTTP response code 200 but dereference unexpected content, are ubiquitous in today's browsing experience. We use Internet search engines to relocate such missing pages and provide means that help automate the rediscovery process. We propose querying web pages' titles against search engines. We investigate the retrieval performance of titles and compare them to lexical signatures which are derived from the pages' content. Since titles naturally represent the content of a document they intuitively change over time. We measure the edit distance between current titles and titles of copies of the same pages obtained from the Internet Archive and display their evolution. We further investigate the correlation between title changes and content modifications of a web page over time. Lastly we provide a predictive model for the quality of any given web page title in terms of its discovery performance. Our results show that titles return more than 60% URIs top ranked and further relevant content returned in the top 10 results. We show that titles decay slowly but are far more stable than the pages' content. We further distill stop titles than can help identify insufficiently performing search engine queries.

= ^ + EN RW G Parallel browsing behavior on the web Information searching / Huang, Jeff / White, Ryen W. Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.13-18

Keywords: log mining, parallel browsing, tabs

doi.acm.org/10.1145/1810617.1810622 ACM Digital Library

Summary: Parallel browsing describes a behavior where users visit Web pages in multiple concurrent threads. Web browsers explicitly support this by providing tabs. Although parallel browsing is more prevalent than linear browsing online, little is known about how users perform this activity. We study the use of parallel browsing through a log-based study of millions of Web users and present findings on their behavior. We identify a power law distribution in browser metrics comprising "outclicks" and tab switches, which signify the degree of parallel browsing. We find that users switch tabs at least 57.4% of the time, but user activity, measured in pageviews, is split among tabs rather than increasing overall activity. Finally, analysis of a subset of the logs focused on Web search shows that while the majority of users do not branch from search engine result pages, the degree of branching is higher for non-navigational queries. Our findings have design implications for Web sites and browsers, search interfaces, and log analysis.

= ^ + EN RW G A semiotic approach for the generation of themed photo narratives Information searching / Hargood, Charlie / Millard, David E. / Weal, Mark J. Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.19-28

Keywords: folksonomies, narrative, narrative generation, semiotics, thematics

doi.acm.org/10.1145/1810617.1810623 ACM Digital Library

Summary: A wide variety of systems could be considered 'narrative systems', either directly working towards generating rich narratives or, more frequently, because they present or handle information in a narrative context. These narratives, generated or otherwise handled, may contain themes; an essential part of the subtext of narrative communicating important concepts outside the capabilities of the literal meaning of the content and forming the thematic cohesion that aids the flow of the presented narrative. However despite this very little work has been undertaken to understand of take advantage of these themes, particularly in narrative generation where the presence of well defined themes may improve the richness of those generated narratives. In this paper we evaluate the performance of a system utilising a thematic model in order to generate simple narratives in the form of photo montages compared to a keyword based system that does not. The experiment demonstrates that the system utilising the thematic model is capable of successfully connoting themes within these narratives. It also shows that the relevance of the resulting narratives to the titles used to generate them is higher in the thematic system than those generated by the other system.

= ^ + EN RW G The impact of bookmarks and annotations on refinding information Information searching / Kawase, Ricardo / Papadakis, George / Herder, Eelco / Nejdl, Wolfgang Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.29-34

Keywords: evaluation, information refinding, user study, web annotation

doi.acm.org/10.1145/1810617.1810624 ACM Digital Library

Summary: Refinding information has been interwoven with web activity since its early beginning. Even though all common web browsers were equipped with a history list and bookmarks early enough to facilitate this need, most users typically use search engines to refind information. However, both bookmarks and search based tools have significant limitations that impact their usability: the former are known to be hard to manage over the course of time, whereas the latter require the user to recall a specific combination of keywords or context. Most importantly, though, both are particularly inappropriate in cases where a piece of information is contained within an unstructured web page. In this paper, we present in-context annotation as a more efficient alternative to these methodologies. To verify this claim, we conducted a study in which we compare the performance of experienced users in all three approaches while revisiting specific pieces of information in the web after a long period of time. The outcomes suggest that in-context annotation clearly outperforms both traditional strategies.

= ^ + EN RW G Automatic construction of travel itineraries using social breadcrumbs Recommenders / De Choudhury, Munmun / Feldman, Moran / Amer-Yahia, Sihem / Golbandi, Nadav / Lempel, Ronny / Yu, Cong Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.35-44

Keywords: flickr, geo-tags, mechanical turk, orienteering problem, social media, travel itinerary

doi.acm.org/10.1145/1810617.1810626 ACM Digital Library

Summary: Vacation planning is one of the frequent -- but nonetheless laborious -- tasks that people engage themselves with online; requiring skilled interaction with a multitude of resources. This paper constructs intra-city travel itineraries automatically by tapping a latent source reflecting geo-temporal breadcrumbs left by millions of tourists. For example, the popular rich media sharing site, Flickr, allows photos to be stamped by the time of when they were taken and be mapped to Points Of Interests (POIs) by geographical (i.e. latitude-longitude) and semantic (e.g., tags) metadata. Leveraging this information, we construct itineraries following a two-step approach. Given a city, we first extract photo streams of individual users. Each photo stream provides estimates on where the user was, how long he stayed at each place, and what was the transit time between places. In the second step, we aggregate all user photo streams into a POI graph. Itineraries are then automatically constructed from the graph based on the popularity of the POIs and subject to the user's time and destination constraints. We evaluate our approach by constructing itineraries for several major cities and comparing them, through a "crowd-sourcing" marketplace (Amazon Mechanical Turk), against itineraries constructed from popular bus tours that are professionally generated. Our extensive survey-based user studies over about 450 workers on AMT indicate that high quality itineraries can be automatically constructed from Flickr data.

= ^ + EN RW G Speak the same language with your friends: augmenting tag recommenders with social relations Recommenders / Liu, Kaipeng / Fang, Binxing / Zhang, Weizhe Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.45-50

Keywords: personalization, social tagging, tag recommendation

doi.acm.org/10.1145/1810617.1810627 ACM Digital Library

Summary: Many existing tag recommendation approaches ignore the social relations between users. In this paper, we investigate the role of such additional information for the task of personalized tag recommendation. We inject the social relations between users and the content similarities between resources, along with the social annotations made by collaborative users, into a graph representation. To fully explore the structure of this graph, we exploit the methodology of random-walk computation of similarities between all the objects. We develop a personalized collaborative filtering algorithm that combines both the collaborative information and the personalized tag preferences. Experiments on Delicious data demonstrate the effectiveness of the proposed methods.

= ^ + EN RW G Connecting users and items with weighted tags for personalized item recommendations Recommenders / Liang, Huizhi / Xu, Yue / Li, Yuefeng / Nayak, Richi / Tao, Xiaohui Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.51-60

Keywords: personalization, recommender systems, tags, web 2.0

doi.acm.org/10.1145/1810617.1810628 ACM Digital Library

Summary: Tags are an important information source in Web 2.0. They can be used to describe users' topic preferences as well as the content of items to make personalized recommendations. However, since tags are arbitrary words given by users, they contain a lot of noise such as tag synonyms, semantic ambiguities and personal tags. Such noise brings difficulties to improve the accuracy of item recommendations. To eliminate the noise of tags, in this paper we propose to use the multiple relationships among users, items and tags to find the semantic meaning of each tag for each user individually. With the proposed approach, the relevant tags of each item and the tag preferences of each user are determined. In addition, the user and item-based collaborative filtering combined with the content filtering approach are explored. The effectiveness of the proposed approaches is demonstrated in the experiments conducted on real world datasets collected from Amazon.com and citeULike website.

= ^ + EN RW G Topic-based personalized recommendation for collaborative tagging system Recommenders / Guo, Yanhui / Joshi, James B. D. Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.61-66

Keywords: collaborative tagging, latent topic models, personalization, recommendation

doi.acm.org/10.1145/1810617.1810629 ACM Digital Library

Summary: Collaborative tagging has become a very popular way to share, annotate, and discover online resources in Web 2.0. Yet as the number of resources in Collaborative tagging system grows over time, sifting through the large amounts of resources and finding the right resources to recommend to the right user is becoming a challenging problem. In this paper, we investigate a probabilistic generative model for collaborative tagging, explore the implicit semantic connections in the sparse and noisy information space of heterogeneous users and unsupervised tagging. First, a modified Latent Dirichlet Allocation (LDA) model is used to cluster the tags and users simultaneously. The generalization of resource description and user could alleviate the tag noise and data sparseness of recommendation effectively. And then, considering that topic-based recommendation only takes the users' global interest into consideration without the capability of distinguishing users' interest in detail, we combine the global interests with the individual interest and community interest. Experimental results demonstrate the topic-based personalized recommendation method, which integrate both the commonality factor among users and the specialties of individuals, could alleviate data sparsity and provide a more flexible and effective recommendation than previous methods.

= ^ + EN RW G Providing resilient XPaths for external adaptation engines Adaptation / Paz, Iñaki / Díaz, Oscar Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.67-76

Keywords: change resilience, evolution, external adaptation, xpath

doi.acm.org/10.1145/1810617.1810631 ACM Digital Library

Summary: Approaches to Web application adaptation can be classified based on whether the application is aware of the adaptation or not. In the latter case, adaptation is referred to as external. External adaptation requires the use of addressing patterns that locate the target portion/data on the application pages to be adapted. Unfortunately, changes on the application normally also require updates to the addressing patterns. This raises pattern robustness as a main concern. This papers focuses on the (semi) automatic generation of change-resilience XPath patterns. Two different categories of changes are addressed, i.e. in space (e.g., different personalizations of a page) and in time (e.g., site upgrades), by exploiting two different techniques: induction and simulated annealing. These techniques permit to obtain XPath patterns "resilient-enough" to a "controlled set of page designs". SiSy, a tool that assists the user in obtaining resilient XPath expressions, was born out of this approach. The approach is tested for two websites (www.yahoo.com and www.elmundo.es), identifying 23 updates to which XPath expressions were resilient to 62% of the undertaken changes.

= ^ + EN RW G The influence of adaptation on hypertext structures and navigation Adaptation / Ramos, Vinicius Faria Culmant / de Bra, Paul M. E. Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.77-82

Keywords: adaptive hypermedia, evaluation, navigation, structural analysis

doi.acm.org/10.1145/1810617.1810632 ACM Digital Library

Summary: In adaptive hypertexts the user is guided in two ways: through the existence of link and through link annotation or hiding. Link structures have been investigated, starting with Botafogo et al, and the effect of link annotation has been studied, for instance by Brusilovsky et al. This paper studies the combined effect of link structure and annotation/hidin on the navigation patterns of users. It defines empirical hubs and studies their correlation with hubs as defined by Kleinberg without considering adaptation. The data for the analysis have been extracted from the logs of the course "Hypermedia Structures and Systems," an online adaptive course offered at the Eindhoven University of Technology.

= ^ + EN RW G The next generation authoring adaptive hypermedia: using and evaluating the MOT3.0 and PEAL tools Adaptation / Foss, Jonathan G. K. / Cristea, Alexandra I. Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.83-92

Keywords: adaptive hypermedia, authoring tools, lag, laos, mot

doi.acm.org/10.1145/1810617.1810633 ACM Digital Library

Summary: Adaptive hypermedia allows for customization to the needs of the user. The authoring process however is not trivial, and is often the main hurdle to overcome in order to bring this useful paradigm to a greater number of users. In this paper, we discuss the major problems occurring in authoring of adaptive hypermedia, and propose a set of generic authoring imperatives, to be consulted by any system implementing creation tools for customization of content. Based on these imperatives, in this paper we extensively illustrate and discuss recent extensions and improvements we have implemented in the My Online Teacher (MOT) adaptation authoring tool set, including the MOT3.0 content authoring and labeling tool and the PEAL adaptation strategy author. Furthermore, we evaluate, compare and discuss two long term uses of the MOT tool set, first in 2008 and the second in 2009.

= ^ + EN RW G Provenance meets adaptive hypermedia Adaptation / Knutov, Evgeny / De Bra, Paul / Pechenizkiy, Mykola Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.93-98

Keywords: adaptation questions, adaptive hypermedia, provenance, w7 provenance model

doi.acm.org/10.1145/1810617.1810634 ACM Digital Library

Summary: In this paper we consider provenance modelling in Adaptive Hypermedia Systems (AHS). We revisit adaptation and data provenance questions and bring up new and complementary aspects of adaptation and provenance, showing similar and supplementing characteristics. We also scrutinize the provenance importance and issues in Adaptive Hypermedia (AH). The aim of this paper is to extend the conventional AH classification questions with the notion of data lineage which essentially plays an important role in adaptation.

= ^ + EN RW G Assisting two-way mapping generation in hypermedia workspace Algorithms and methods / Hsieh, Haowei / Pauls, Katherine / Jansen, Amber / Nimmagadda, Gautam / Shipman, Frank Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.99-108

Keywords: editable visualizations, information visualization, information workspace, spatial hypertext, two-way mappings

doi.acm.org/10.1145/1810617.1810636 ACM Digital Library

Summary: This paper reports our study of a two-way mapping generation tool called Mapping Assistant, as an extension to the Spatial Hypermedia system VITE. Mapping Assistant has been designed to overcome the problem arising due to the difficulty of users in generating an initial two-way mapping for VITE. We have developed VITE to allow users to interact with information in a semi-formal workspace. Creating two-way mapping profiles is a vital step for projecting structured information into a spatial hypermedia system. A previous study of VITE indicated that users spent much of their time developing an initial mapping before working on the information task. We designed the Mapping Assistant to assist users by generating a quick initial mapping from the data entered by the user and reduce the cognitive and mental load on the user. This research studies users' impression of the Mapping Assistant. The results indicate that the users liked the Mapping Assistant and found it useful, but comments from users also reveal possible directions for further improvement of the tool and its design.

= ^ + EN RW G Analysis of graphs for digital preservation suitability Algorithms and methods / Cartledge, Charles L. / Nelson, Michael L. Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.109-118

Keywords: resilience, robustness, small world

doi.acm.org/10.1145/1810617.1810637 ACM Digital Library

Summary: We investigate the use of autonomically created small-world graphs as a framework for the long term storage of digital objects on the Web in a potentially hostile environment. We attack the classic Erdos -- Renyi random, Barabási and Albert power law, Watts -- Strogatz small world and our Unsupervise. Small World (USW) graphs using different attacker strategies and report their respective robustness. Using different attacker profiles, we construct a game where the attacker is allowed to use a strategy of his choice to remove a percentage of each graph's elements. The graph is then allowed to repair some portion of its self. We report on the number of alternating attack and repair turns until either the graph is disconnected, or the game exceeds the number of permitted turns. Based on our analysis, an attack strategy that focuses on removing the vertices with the highest betweenness value is most advantageous to the attacker. Power law graphs can become disconnected with the removal of a single edge; random graphs with the removal of as few as 1% of their vertices, small-world graphs with the removal of 14% vertices, and USW with the removal of 17% vertices. Watts -- Strogatz small-world graphs are more robust and resilient than random or power law graphs. USW graphs are more robust and resilient than small world graphs. A graph of USW connected WOs filled with date could outlive the individuals and institutions that created the data in an environment where WOs are lost due to random failures or directed attacks.

= ^ + EN RW G iMapping: a zooming user interface approach for personal and semantic knowledge management Algorithms and methods / Haller, Heiko / Abecker, Andreas Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.119-128

Keywords: human-computer interaction, interaction design, personal knowledge management, semantic desktop, spatial hypertext, visual knowledge mapping

doi.acm.org/10.1145/1810617.1810638 ACM Digital Library

Summary: We present iMapping, a zooming based approach for visually organizing information objects. It was developed on top of semantic desktop technologies and especially targets the support of personal knowledge management. iMapping has been designed to combine the advantages of spatial hypertext and other proven visual mapping approaches like mind-mapping and concept mapping, which are incompatible in their original form. We describe the design and prototypical implementation of iMapping -- which is fundamentally based on deep zooming and nesting. iMapping bridges the gap between unstructured content like informal text notes and semantic models by allowing annotations with the whole range from vague associations to formal relations. First experimental evaluation of the iMapping user-interface approach indicates favorable user experience and functionality, compared with state-of-the-art Mind-Mapping software.

= ^ + EN RW G Modularity for heterogeneous networks Networked communities / Murata, Tsuyoshi Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.129-134

Keywords: complex network

doi.acm.org/10.1145/1810617.1810640 ACM Digital Library

Summary: Online social media such as delicious and digg are represented as tripartite networks whose vertices are users, tags, and resources. Detecting communities from such tripartite networks is practically important. Modularity is often used as the criteria for evaluating the goodness of network divisions into communities. Although Newman-Girvan modularity is popular for unipartite networks, it is not suitable for n-partite networks. For bipartite networks, Barber, Guimera, Murata and Suzuki define bipartite modularities. For tripartite networks, Neubauer defines tripartite modularity which extends Murata's bipartite modularity. However, Neubauer's tripartite modularity still uses projections and it will lose information that original tripartite networks have. This paper proposes new tripartite modularity for tripartite networks that do not use projections. Experimental results show that better community structures can be detected by optimizing our tripartite modularity.

= ^ + EN RW G Link prediction applied to an open large-scale online social network Networked communities / Corlette, Dan / Shipman, Frank M., III Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.135-140

Keywords: link prediction, network dynamics, social networks

doi.acm.org/10.1145/1810617.1810641 ACM Digital Library

Summary: In this paper, we describe experiments examining the practicality of applying link prediction to an open large-scale online social network. We rely on metrics that are strictly topological, making use of one previously identified metric and one of our own. We directly address the open nature of the network through a study of the linking dynamics over time between users and the effect the openness of the network (i.e. users entering/leaving the network) has on our ability to predict new friendship links. We follow users from the time they enter the network to 10 months after joining and examine the effect of applying link prediction at different points. Analysis shows that prediction results are best shortly after users have entered the network and that the precision and recall of link prediction results diminish the longer users have been members of the network. To the best of our knowledge, our analysis is the most comprehensive in terms of analyzing link prediction in an open large-scale online social network.

= ^ + EN RW G Community-based ranking of the social web Networked communities / Kashoob, Said / Caverlee, James / Kamath, Krishna Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.141-150

Keywords: community, ranking, social, tagging

doi.acm.org/10.1145/1810617.1810642 ACM Digital Library

Summary: The rise of social interactions on the Web requires developing new methods of information organization and discovery. To that end, we propose a generative community-based probabilistic tagging model that can automatically uncover communities of users and their associated tags. We experimentally validate the quality of the discovered communities over the social bookmarking system Delicious. In comparison to an alternative generative model (Latent Dirichlet Allocation (LDA), we find that the proposed community-based model improves the empirical likelihood of held-out test data and discovers more coherent interest-based communities. Based on the community-based probabilistic tagging model, we develop a novel community-based ranking model for effective community-based exploration of socially-tagged Web resources. We compare community-based ranking to three state-of-the-art retrieval models: (i) BM25; (ii) Cluster-based retrieval using K-means clustering; and (iii) LDA-based retrieval. We find that the proposed ranking model results in a significant improvement over these alternatives (from 7% to 22%) in the quality of retrieved pages.

= ^ + EN RW G Social networks and interest similarity: the case of CiteULike Networked communities / Lee, Danielle H. / Brusilovsky, Peter Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.151-156

Keywords: citeulike, information sharing, social networks

doi.acm.org/10.1145/1810617.1810643 ACM Digital Library

Summary: In collaborative filtering recommender systems, there is little room for users to get involved in the choice of their peer group. It leaves users defenseless against various spamming or ''shilling'' attacks. Other social Web-based systems, however, allow users to self-select peers and build a social network. We argue that users' self-defined social networks could be valuable to increase the quality of recommendation in CF systems. To prove the feasibility of this idea we examined how similar are interests of users connected by self-defined relationships in a collaborative tagging systems Citeulike. Interest similarity was measured by similarity of items and meta-data they share and tags they use. Our study shows that users connected by social networks exhibit significantly higher similarity on all explored levels (items, meta-data, and tags) than non-connected users. This similarity is the highest for directly connected users and decreases with the increase of distance between users. Among other interesting properties of information sharing is the finding that between-user similarity in social connections on the level of metadata and tags is much larger than similarity on the level of items. Overall, our findings support the feasibility of social network based recommender systems and offer some good hints to the prospective authors of these systems.

= ^ + EN RW G Of categorizers and describers: an evaluation of quantitative measures for tagging motivation Tagging / Körner, Christian / Kern, Roman / Grahsl, Hans-Peter / Strohmaier, Markus Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.157-166

Keywords: measures, social software, tagging, user motivation

doi.acm.org/10.1145/1810617.1810645 ACM Digital Library

Summary: While recent research has advanced our understanding about the structure and dynamics of social tagging systems, we know little about (i) the underlying motivations for tagging (why users tag), and (ii) how they influence the properties of resulting tags and folksonomies. In this paper, we focus on problem (i) based on a distinction between two types of user motivations that we have identified in earlier work: Categorizers vs. Describers. To that end, we systematically define and evaluate a number of measures designed to discriminate between describers, i.e. users who use tags for describing resources as opposed to categorizers, i.e. users who use tags for categorizing resources. Subsequently, we present empirical findings from qualitative and quantitative evaluations of the measures on real world tagging behavior. In addition, we conducted a recommender evaluation in which we study the effectiveness of each of the presented measures and found the measure based on the tag content to be the most accurate in predicting the user behavior closely followed by a content independent measure. The overall contribution of this paper is the presentation of empirical evidence that tagging motivation can be approximated with simple statistical measures. Our research is relevant for (a) designers of tagging systems aiming to better understand the motivations of their users and (b) researchers interested in studying the effects of users' tagging motivation on the properties of resulting tags and emergent structures in social tagging systems.

= ^ + EN RW G Of kings, traffic signs and flowers: exploring navigation of tagged documents Tagging / Gwizdka, Jacek Proceedings of the 21st ACM Conference on Hypertext and Hypermedia 2010 p.167-172

Keywords: information space metaphors, pivot browsing, tag clouds

doi.acm.org/10.1145/1810617.1810646 ACM Digital Library

Summary: Many popular Web 2.0 sites support navigation of tagged web resources. The tag-based navigation has been described as a lightweight reorientation of view on tags and the associated web resources. But is this navigation really lightweight? This paper briefly presents an interface created to support navigation of tagged documents. The paper then describes a study that explored users' understanding of the tag-based navigation process and the underlying information space. The results point to difficulties in promoting correct understanding of complex relationships between documents and tags and to the need for creating interfaces that support navigation continuity.