Thesis (M. A.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.

Much structured data of scientific interest can be represented as networks, where sets of nodes or vertices are joined together in pairs by links or edges. Although these networks may belong to different research areas, there is one property that many of them do have in common: the network community structure, which means that there exists densely connected groups of vertices, with only sparser connections between groups. The main goal of community mining is to discover these communities in social networks or other similar information network environments. We face many deficiencies in current community structure discovery methods. First, one similarity metric is typically applied in all networks, without considering the differences in network and application characteristics. Second, many existing methods assume the network information is fully available, and one node only belongs to one cluster. However, in reality, a social network can be huge thus it is hard to access the complete network. It is also common for social entities to belong to multiple communities. Finally, relations between entities are hard to understand in heterogeneous social networks, where multiple types of relations and entities exist. Therefore, the thesis of this research is to tackle these community mining problems, in order to discover and evaluate community structures in social networks from various aspects.

Contemporary networking in Canada, like most of the developed world, involves significant use of media to maintain relationships. This is not the use of media for faraway alters where in person contact is difficult, but media use within the very fabric of everyday life alongside in person contact. Past debates about the effects of new media have frequently focused on a medium's potential for social isolation. These debates have resulted in ambiguous, muted or contradictory findings. So instead of suggesting another response to the issue of social isolation, this thesis reorients the focus towards a different question: under what conditions are alters accessible and how does multiple media use affect this accessibility? Rather than suggest that new media simply offer "more" social accessibility, I contend that they complicate social accessibility by offering individuals increasingly differentiated ways to habitually maintain contact with each other. The result of this differentiation is that while individuals might be able to maintain contact with more alters (or at least just as many) in the abstract sense, they end up maintaining contact with the most accessible alters rather than alters with whom one has the strongest ties. This is the conundrum of multiple media use: how is it that each individual medium offers increased convenience but the sum total of media use makes life less convenient, more planned and more complicated? I suggest it is because media use cuts across longstanding social norms of public and private spaces (or public and private time) without offering a coherent normative framework as a substitute. Instead, individuals are differentially accessible via each medium. Moreover, this accessibility is related more to emergent personal habits than to tie strength. Data for this study comes from 350 random-sample surveys and 86 follow-up social network-oriented interviews in East York, a former borough on the east side of downtown Toronto, Canada. The data were collected in 2005, before the widespread adoption of social networking software, but after the widespread adoption of cellular telephones, instant messaging services and email.

Contemporary networking in Canada, like most of the developed world, involves significant use of media to maintain relationships. This is not the use of media for faraway alters where in person contact is difficult, but media use within the very fabric of everyday life alongside in person contact. Past debates about the effects of new media have frequently focused on a medium's potential for social isolation. These debates have resulted in ambiguous, muted or contradictory findings. So instead of suggesting another response to the issue of social isolation, this thesis reorients the focus towards a different question: under what conditions are alters accessible and how does multiple media use affect this accessibility? Rather than suggest that new media simply offer "more" social accessibility, I contend that they complicate social accessibility by offering individuals increasingly differentiated ways to habitually maintain contact with each other. The result of this differentiation is that while individuals might be able to maintain contact with more alters (or at least just as many) in the abstract sense, they end up maintaining contact with the most accessible alters rather than alters with whom one has the strongest ties. This is the conundrum of multiple media use: how is it that each individual medium offers increased convenience but the sum total of media use makes life less convenient, more planned and more complicated? I suggest it is because media use cuts across longstanding social norms of public and private spaces (or public and private time) without offering a coherent normative framework as a substitute. Instead, individuals are differentially accessible via each medium. Moreover, this accessibility is related more to emergent personal habits than to tie strength. Data for this study comes from 350 random-sample surveys and 86 follow-up social network-oriented interviews in East York, a former borough on the east side of downtown Toronto, Canada. The data were collected in 2005, before the widespread adoption of social networking software, but after the widespread adoption of cellular telephones, instant messaging services and email.

Thesis (Ph. D.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves 141-145).

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Social bookmarking has gained popularity since the advent of Web 2.0. Keywords known as tags are created to annotate web content, and the resulting tag space composed of the tags, the resources, and the users arises as a new platform for web content discovery. Useful and interesting web resources can be located through searching and browsing based on tags, as well as following the user-user connections formed in the social bookmarking community. However, the effectiveness of tag-based search is limited due to the lack of explicitly represented semantics in the tag space. In addition, social connections between users are underused for web content discovery because of the inadequate social functions. In this research, we propose a comprehensive framework to reorganize the flat tag space into a hierarchical faceted model. We also studied the structure and properties of various networks emerging from the tag space for the purpose of more efficient web content discovery.The major research approach used in this research is social network analysis (SNA), together with methodologies employed in design science research. The contribution of our research includes: (i) a faceted model to categorize social bookmarking tags; (ii) a relationship ontology to represent the semantics of relationships between tags; (iii) heuristics to reorganize the flat tag space into a hierarchical faceted model using analysis of tag-tag co-occurrence networks; (iv) an implemented prototype system as proof-of-concept to validate the feasibility of the reorganization approach; (v) a set of evaluations of the social functions of the current networking features of social bookmarking and a series of recommendations as to how to improve the social functions to facilitate web content discovery.

A database schema should consist of structures and semantic integrity constraints. Se mantic integrity constraints (SICs) are invariant restrictions on the static states of the stored data and the state transitions caused by the primitive operations: insertion, dele tion, or update. Traditionally, database design has been carried out on an ad hoc basis and focuses on structure and efficiency. Although the E-R model is the popular concep tual modelling tool, it contains few inherent SICs. Also, although the relational database model is the popular logical data model, a relational database in fourth or fifth normal form may still represent little of the data semantics. Most integrity checking is distributed to the application programs or transactions. This approach to enforcing integrity via the application software causes a number of problems. Recently, a number of systems have been developed for assisting the database design process. However, only a few of those systems try to help a database designer incorporate SICs in a database schema. Furthermore, current SIC representation languages in the literature cannot be used to represent precisely the necessary features for specifying declarative and operational semantics of a SIC, and no modelling tool is available to incorporate SICs. This research solves the above problems by presenting two models and one subsystem. The E-R-SIC model is a comprehensive modelling tool for helping a database designer in corporate SICs in a database schema. It is application domain-independent and suitable for implementation as part of an automated database design system. The SIC Repre sentation model is used to represent precisely these SICs. The SIC elicitation subsystem would verify these general SICs to a certain extent, decompose them into sub-SICs if necessary, and transform them into corresponding ones in the relational model. A database designer using these two modelling tools can describe more data semantics than with the widely used relational model. The proposed SIC elicitation subsystem can provide more modelling assistance for him (her) than current automated database design systems.

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