Ioannis Papadakis

Interactive Search Results

In this paper, we address the issue of interactive search results manipulation, as provided by typical Web-based information retrieval modules like search engines and directories. Many digital library systems could benefit a lot from the proposed approach, since it is heavily based on metadata, which constitute the building block of such systems. We also propose a way of ranking search results according to their overall importance, which is defined as a weighted combination of the relevancy and popularity of a resource that is being referenced in a search results list. In order to evaluate this model, we have developed an interactive search results manipulation application, which is executed at the clients workspace through a Web browser without any further interaction with the server that provided the initial search results list. The prototype implementation is based on the XML standard and has been evaluated through an adequate evaluation process from which useful conclusions have been obtained.

Adding Temporal Dimension to Ontologies via OWL Reification

It has been pointed out recently by many researchers that it is difficult for languages such as OWL to incorporate time in their relations. As a result it is difficult to reason about the temporal ordering of events or about the temporal properties of relations that vary as a function of time. There are a number of methods that have been proposed in order to circumvent this difficulty. One technique that can be used for this purpose is reification. The advantage of this approach is that it does not require the introduction of additional constructs to the OWL language. In this work we investigate the types of queries that are possible with this mechanism and we conclude that is in fact possible to express many interesting and useful queries. Moreover, due to the use of standard OWL, existing reasoning tools are capable of handling these queries.

Secure medical digital libraries

In this paper, a secure medical digital library is presented. It is based on the CORBA specifications for distributed systems. The described approach relies on a three-tier architecture. Interaction between the medical digital library and its users is achieved through a Web server. The choice of employing Web technology for the dissemination of medical data has many advantages compared to older approaches, but also poses extra requirements that need to be fulfilled. Thus, special attention is paid to the distinguished nature of such medical data, whose integrity and confidentiality should be preserved at all costs. This is achieved through the employment of Trusted Third Parties (TTP) technology for the support of the required security services. Additionally, the proposed digital library employs smartcards for the management of the various security tokens that are used from the above services.

Visualizing OPAC subject headings

Purpose – This paper aims at providing a robust, user‐friendly and efficient navigation procedure in an online library catalog that is based on semantic information encapsulated within subject headings.Design/methodology/approach – The paper describes an interactive navigation procedure inside an online library catalog based on semantic information. The proposed approach is presented through a web‐based, prototype application following the most recent trends of the semantic web such as AJAX technology and the web ontology language – OWL for encoding semantics.Findings – According to the proposed method, a GUI interface exposes the hierarchy of the subject headings employed within an OPAC, as well as all stated relations between such headings, as links that the user can follow, effectively traversing the ontology and formulating at the same time the actual query to the underlying OPAC. This act of interactive navigation through the librarys assets aids searchers in accurately formulating their queries, by...

DocML: A digital library of University data

This paper presents DocML, a Web‐based digital library of university data. The goal is to build a system capable of preserving and managing student assignments efficiently in a university environment. It is based on a three‐tier architecture that is typical for distributed Web applications. Communication between the layers of the digital library and the architectural components that reside in the middle layer is facilitated through an XML standard. XML is also used for the development of a distributed metadata management system that describes the location and content of the digital library’s documents.

Virtual Worlds as Information Spaces: Supporting Semantic and Social Navigation in a shared 3D Environment

Virtual worlds are a popular medium for communication and collaboration in 3D and they are being used as shared information spaces in various application areas. However, compared to traditional hypermedia and web-based information systems they offer little support for semantic and social navigation. In this paper, a framework for enhancing virtual worlds with metaphors that support improved semantic and social browsing in the 3D environment is proposed, and an integrated architecture for their interface with external information sources through the employment of Linked Data is presented. In order to assess the effectiveness of the proposed approach, a prototype system has been implemented and accordingly evaluated.

Visualizing Ontologies on the Web

The proposed paper introduces an ontology visualization model suitable for average web users. It is capable of retaining ontology expressiveness while at the same time hiding the formal terminology that is usually employed in the context of ontology development. According to the proposed ontology visualization model, classes are represented as boxes and their corresponding properties are represented as labeled lines connecting such boxes. By hoping from one box to another, users are able to interactively explore the underlying ontology. Such interaction is facilitated through an intuitive, web-based GUI implemented in Javascript, which communicates with the underlying ontology through a middleware component implemented in Python.

Top-K Shortest Paths in Large Typed RDF Datasets Challenge

Perhaps the most widely appreciated linked data principle instructs linked data providers to provide useful information using the standards (i.e., RDF and SPARQL). Such information corresponds to patterns expressed as SPARQL queries that are matched against the RDF graph. Until recently, patterns had to specify the exact path that would match against the underlying graph. The advent of the SPARQL 1.1 Recommendation introduced property paths as a new graph matching paradigm that allows the employment of Kleene star * (and its variant Kleene plus +) unary operators to build SPARQL queries that are agnostic of the underlying RDF graph structure. In this paper, we present the Top-k Shortest Paths in large typed RDF Datasets Challenge. It highlights the key aspects of property path queries that employ the Kleene star operator, presenting three widely different approaches.

Highlighting Timely Information in Libraries Through Social and Semantic Web Technologies

Until now, timeliness of information in libraries is commonly used to underpin collection development and is directly related to quality in terms of realizing whether information is sufficiently up-to-date and available for use.

Providing LOD-Based Functionality in Digital Libraries

Libraries and other memory institutions have wasted no time in realizing that linked data technologies provide the necessary means to solve important interoperability issues that have been plaguing the community for decades. Despite the wide availability of cultural heritage information as linked open data – LOD, there seems to be a lack of LOD services that are targeted towards the end-user. In this paper, a LOD-powered, subject-based browsing service is proposed, capable of integrating resources from diverse repositories. More specifically, the proposed work describes a service that is built on top of a DSpace-based digital library of thesis and dissertations that not only exposes its topical information (i.e. subject headings) to the wider linked data community, but also manages to provide its end-users with additional relevant resources originating from a remote repository (i.e. New York Times – NYT articles database). The proposed service has been accordingly evaluated through a user survey.