DEPARTAMENTO DE INFORMATICA (COMPUTER SCIENCES DEPARTMENT) Doctoral Programme: INFORMATION TECHNOLOGY, COMMUNICATIONS AND COMPUTATIONAL MATHEMATICS SEMANTICALLY-ENHANCED ADVERTISEMENT RECOMMENDER SYSTEMS IN SOCIAL NETWORKS Doctoral Thesis by Ali Pazahr Under the supervision of Dr. J. Javier Samper Zapater Dr. Francisco García Sánchez Valencia, May 2017 D. José Javier Samper Zapater, Profesor Contratado Doctor del Departamento de Informática de la Universidad de Valencia, y D. Francisco García Sánchez, Profesor Titular de Universidad del Departamento de Informática y Sistemas de la Universidad de Murcia, CERTIFICAN QUE: La presente Tesis Doctoral original de D. Ali Pazahr titulada “SEMANTICALLY-ENHANCED ADVERTISEMENT RECOMMENDER SYSTEMS IN SOCIAL NETWORKS”, ha sido realizada bajo nuestra dirección y supervisión y, a nuestro juicio, reúne los requisitos para su lectura y obtención del grado de Doctor. Y para que así conste a los efectos oportunos, firmamos el presente certificado en Valencia, a 16 de mayo de 2017. Prof. Dr. José Javier Samper Zapater Prof. Dr. Francisco García Sánchez Index of contents INDEX OF CONTENTS Index of contents........................................................................................................................... 5 Index of figures .............................................................................................................................. 9 Index of tables ............................................................................................................................. 11 Acknowledgements ..................................................................................................................... 13 Overview ..................................................................................................................................... 15 SECTION I: Introduction ............................................................................................................... 19 Chapter 1 ..................................................................................................................................... 21 1. Introduction: approach to the problem .............................................................................. 21 1.1 Identification of the problem ......................................................................................... 21 1.2 Motivation ...................................................................................................................... 26 1.3 Research Questions ........................................................................................................ 27 1.4 Objectives ....................................................................................................................... 27 1.5 Methodology of research, work plan ............................................................................. 29 1.6 Summary ........................................................................................................................ 32 SECTION II: Theoretical foundations, technologies and state of the art .................................... 35 Chapter 2 ..................................................................................................................................... 37 2. Definitions (Literature Study) .............................................................................................. 37 2.1 Introduction ................................................................................................................... 37 2.2 Semantic Web ................................................................................................................ 39 2.2.1 Purpose ................................................................................................................ 39 2.2.2 Standards ............................................................................................................. 42 2.2.3 Projects ................................................................................................................ 44 2.2.4 Common Semantic Web technologies and terms ............................................... 45 2.2.5 Other aspect to the Semantic Web ..................................................................... 47 2.2.6 Ontology .............................................................................................................. 48 2.3 Social web....................................................................................................................... 51 2.3.1 The Evolving Social Web ...................................................................................... 53 2.3.2 From the Social Web to Real Life ........................................................................ 55 2.3.3 Social Networks ................................................................................................... 57 2.4 Social Semantic Web ...................................................................................................... 63 2.4.1 Users Semantic Profiles ....................................................................................... 67 2.4.2 Frameworks for Social Networks ........................................................................ 67 2.5 Online Promoting ........................................................................................................... 81 2.5.1 Online advertisement .......................................................................................... 81 5 Index of contents 2.5.2 Competitive benefit over Customary Promoting ................................................ 81 2.5.3 Semantic advertising ........................................................................................... 81 2.5.4 Social Network Advertising ................................................................................. 82 2.6 Recommender Systems .................................................................................................. 82 2.6.1 About recommendation systems ........................................................................ 82 2.6.2 Five Problems of Recommender Systems ........................................................... 83 2.6.3 Role of Social Networks in recommendation systems ........................................ 85 2.6.4 Aim of Recommender Systems ........................................................................... 85 2.6.5 Recommendation Techniques ............................................................................. 89 2.6.6 Role of recommender systems in E-commerce .................................................. 95 2.6.7 Limitations of classical approaches ..................................................................... 95 2.7 Related works ................................................................................................................. 96 2.8 Summary ...................................................................................................................... 105 SECTION III: Proposals and contributions.................................................................................. 107 Chapter 3 ................................................................................................................................... 109 3. Methodology ..................................................................................................................... 109 3.1 Introduction ................................................................................................................. 109 3.2 The Framework ............................................................................................................ 110 3.2.1 Preliminary User Activity ................................................................................... 113 3.2.2 Semantic Recommendation Engine .................................................................. 113 3.3 Case study .................................................................................................................... 118 3.4 Client application ......................................................................................................... 120 3.5 A Test Case ................................................................................................................... 124 3.6 Dataset ......................................................................................................................... 125 3.7 Programming Language ............................................................................................... 127 3.8 Efficiency ...................................................................................................................... 127 3.9 The Security of the Framework .................................................................................... 128 3.9.1 On the level of user entry .................................................................................. 129 3.9.2 On the level of user activity............................................................................... 129 3.10 Summary .................................................................................................................. 132 SECTION IV: Evaluation.............................................................................................................. 135 Chapter 4 ................................................................................................................................... 137 4. Evaluation .........................................................................................................................