Technische Universit¨atM¨unchen Fakult¨atf¨urInformatik Contextual Social Networking Dipl.-Phys., Dipl.-Inform. Dr.rer.nat. Georg Groh Habilitationsschrift Mitglieder des Habilitationskomittees: Prof. Dr. Johann Schlichter Prof. Dr. Bettina Berendt Prof. Dr. Helmut Seidl Kurz-Zusammenfassung Der zentrale Gegenstand der vorliegenden Arbeit ist die vielschichtige Frage, wie Kontexte detektiert und abgeleitet werden k¨onnen,die dazu dienen k¨onnen,neuar- tige kontextbewusste Social Networking Dienste zu schaffen und bestehende Di- enste in ihrem Nutzwert zu verbessern. Die (noch nicht abgeschlossene) erfolgre- iche Umsetzung dieses Programmes f¨uhrtauf ein Konzept, das man als Contextual Social Networking bezeichnen kann. In einem grundlegenden ersten Teil werden die eng zusammenh¨angendenGebiete Contextual Social Networking, Mobile Social Networking und Decentralized Social Networking mit verschiedenen Methoden und unter Fokussierung auf verschiedene Detail-Aspekte n¨aherbeleuchtet und in Zusam- menhang gesetzt. Ein zweiter Teil behandelt die Frage, wie soziale Kurzzeit- und Langzeit-Kontexte als f¨urdas Social Networking besonders interessante Formen von Kontext gemessen und abgeleitet werden k¨onnen. Ein Fokus liegt hierbei auf NLP Methoden zur Charakterisierung sozialer Beziehungen als einer typischen Form von sozialem Langzeit-Kontext. Ein weiterer Schwerpunkt liegt auf Methoden aus dem Mobile Social Signal Processing zur Ableitung sinnvoller sozialer Kurzzeit-Kontexte auf der Basis von Interaktionsgeometrien und Audio-Daten. Es wird ferner unter- sucht, wie pers¨onliche soziale Agenten Kontext-Elemente verschiedener Abstraktion- sgrade miteinander kombinieren k¨onnen.Der dritte Teil behandelt neuartige und verbesserte Konzepte f¨urkontextbewusste Social Networking Dienste. Es werden spezielle Formen von Awareness Diensten, neue Formen von sozialem Information Retrieval, Konzepte f¨urkontextbewusstes Privacy Management und Dienste und Plattformen zur Unterst¨utzungvon Open Innovation und Kreativit¨atuntersucht und vorgestellt. Diese Version der Habilitationsschrift enth¨altdie inkludierten Publikationen zur Vermeidung von Copyright-Verletzungen auf Seiten der Journals u.a. nicht. Kon- takt in Bezug auf die Version mit allen inkludierten Publikationen: Georg Groh, [email protected]. Abstract The thesis centers around the multi-faceted research question of how contexts may be detected and derived that can be used for new context aware Social Networking services and for improving the usefulness of existing Social Networking services, giv- ing rise to the notion of Contextual Social Networking. In a first foundational part, we characterize the closely related fields of Contextual-, Mobile-, and Decentral- ized Social Networking using different methods and focusing on different detailed aspects. A second part focuses on the question of how short-term and long-term social contexts as especially interesting forms of context for Social Networking may be derived. We focus on NLP based methods for the characterization of social re- lations as a typical form of long-term social contexts and on Mobile Social Signal Processing methods for deriving short-term social contexts on the basis of geome- try of interaction and audio. We furthermore investigate, how personal social agents may combine such social context elements on various levels of abstraction. The third part discusses new and improved context aware Social Networking service concepts. We investigate special forms of awareness services, new forms of social information retrieval, social recommender systems, context aware privacy concepts and services and platforms supporting Open Innovation and creative processes. This version of the thesis does not contain the included publications because of copyrights of the journals etc. Contact in terms of the version with all included publications: Georg Groh, [email protected]. iv Contents Introduction1 I Foundations9 1 Contextual Social Networking 11 1.1 Social Networking............................ 11 1.1.1 Web 2.0 and Social Media.................... 12 1.1.2 Technical Aspects........................ 15 1.1.3 Social Media Classes....................... 16 1.1.4 Social Networking........................ 24 1.1.5 Social Networking Services................... 25 1.1.6 SN vs. Community Computing................. 26 1.1.7 Related Scientific Disciplines.................. 26 1.2 Context-Aware Computing and Contextual Social Networking.... 27 1.2.1 Context-Aware Computing................... 28 1.2.2 Contextual Social Networking.................. 30 1.3 Challenges and Opportunities for Future Research.......... 34 1.4 An Early Study on Context-Aware Community Support Systems *. 35 2 Mobile Social Networking 37 2.1 Network-based Scientometric Characterization of the Field MSN *. 37 2.2 Mobile Social Networking Services and Platforms *.......... 39 2.3 Challenges and Opportunities for Future Research.......... 39 3 Architectural Elements of Decentralized Social Networking 41 3.1 Decentralized Social Networking.................... 41 3.1.1 Personal Social Agents...................... 42 3.1.2 Peer-to-Peer Social Networking................. 43 v vi CONTENTS 3.1.3 Social Semantic Web....................... 44 3.1.4 Comparing DSN and CSN Scenarios.............. 44 3.2 Group Management in DSN Scenarios *................ 46 3.3 Challenges and Opportunities for Future Research.......... 46 II Determining Social Context 49 4 Enriching Social Relation Models 51 4.1 Overview of Part II: Detecting and Modeling Social Context..... 51 4.2 Conceptualizations and Other Characterizations for Social Relations 52 4.3 Folksonomies for Social Relations *................... 54 4.4 Characterizing Social Relations via NLP-based Analysis *...... 55 4.5 Challenges and Opportunities for Future Research.......... 57 5 Social Situations I: Geometry of Interaction 59 5.1 Short-Term Social Context and Mobile Sensing............ 59 5.1.1 Mobile Social Signal Processing and Reality Mining..... 60 5.2 Social Situations............................. 62 5.3 Detecting Social Situations via Interaction Geometry......... 68 5.3.1 Infrastructure-Free Measurement of Interaction Geometry.. 70 5.3.2 Detection of and Applications for Social Situations *..... 72 5.4 Challenges and Opportunities for Future Research.......... 74 6 Social Situations II: Audio Signals and the Combination of Evi- dence from Multiple Sources 77 6.1 Audio in Social Signal Processing.................... 78 6.2 Detection of Social Interaction via Turn-Taking Patterns *...... 79 6.3 Speaker Diarization and Direct Audio Based Methods for Social In- teraction Detection............................ 80 6.3.1 General Speaker Diarization................... 80 6.3.2 Specific Approaches for Social Interaction Detection..... 81 6.3.2.1 Problem Conditions and Corpora.......... 82 6.3.2.2 Performance of State of the Art Approaches.... 83 6.3.2.3 Direct Energy-based Detection of Turn Taking and Social Interaction................... 85 6.4 Combining Multiple Evidences for Social Situation Detection *... 91 6.5 Challenges and Opportunities for Future Research.......... 91 CONTENTS vii III Applications of Social Context 93 7 Awareness and Communication Services and Activity Prediction 95 7.1 Overview of Part III: Social Networking Services and Social Context 95 7.2 Awareness and Visualization...................... 96 7.2.1 Visualization of Social Context Dynamics as an Awareness Service in (Mobile) Social Networking............. 96 7.2.2 Hierarchical Temporal Visualization of Communication Events and Resulting Social Relation Abstractions.......... 97 7.2.3 Visualization of Social Network Dynamics *.......... 100 7.2.4 Challenges and Opportunities for Future Research...... 101 7.3 Social Life-Logging & Socio-Casting *................. 102 7.3.1 Social Life-Logging........................ 102 7.3.2 Socio-Casting........................... 105 7.3.3 Challenges and Opportunities for Future Research...... 106 7.4 Social Activity Prediction *....................... 107 7.4.1 Challenges and Opportunities for Future Research...... 108 8 Privacy Management 111 8.1 Privacy Management in Social Networking............... 111 8.2 Inferring Profile Attributes *...................... 112 8.3 Contextual Privacy Management in SN and MSN........... 113 8.3.1 An Online Survey........................ 113 8.3.2 A Study on Context-Aware Privacy Management Concepts in SN................................. 115 8.3.3 Challenges and Opportunities for Future Research...... 118 8.4 Privacy, Information Flow Control and Information Markets..... 119 8.4.1 Contextual Privacy Management Concept *.......... 120 8.4.2 Challenges and Opportunities for Future Research...... 121 9 Information Applications 123 9.1 Information Services........................... 123 9.1.1 Flavors of Services in SN and MSN............... 123 9.1.2 Context and Unconscious Information Needs......... 125 9.1.3 Human IR............................. 127 9.2 An Alternative Information Retrieval Approach for Decentralized SN and MSN *................................ 129 9.2.1 Implementation and Test.................... 132 viii CONTENTS 9.3 Evaluating Alternative IR Principles Based on Human IR...... 135 9.3.1 Evaluation Study......................... 135 9.3.2 Studying Interrelations between Spatio-Temporal, Social and Semantic Contexts........................ 136 9.3.3 Information Retrieval Experiments............... 139 9.4 Challenges and Opportunities for Future Research.......... 143 10 Social Recommender