Akrivi Katifori

Ontology visualization methods—a survey

Ontologies, as sets of concepts and their interrelations in a specific domain, have proven to be a useful tool in the areas of digital libraries, the semantic web, and personalized information management. As a result, there is a growing need for effective ontology visualization for design, management and browsing. There exist several ontology visualization methods and also a number of techniques used in other contexts that could be adapted for ontology representation. The purpose of this article is to present these techniques and categorize their characteristics and features in order to assist method selection and promote future research in the area of ontology visualization.

Ontologies and the brain: Using spreading activation through ontologies to support personal interaction

Ontologies, as knowledge engineering tools, allow information to be modelled in ways resembling to those used by the human brain, and may be very useful in the context of personal information management (PIM) and task information management (TIM). This work proposes the use of ontologies as a long-term knowledge store for PIM-related information, and the use of spreading activation over ontologies in order to provide context inference to tools that support TIM. Details on the ontology creation and content are provided, along with a full description of the spreading activation algorithm and its preliminary evaluation.

Real exhibitions in a virtual museum

When creating a virtual environment open to the public a number of challenges have to be addressed. The equipment has to be chosen carefully in order to be be able to withstand hard everyday usage, and the application has not only to be robust and easy to use, but has also to be appealing to the user, etc. The current paper presents findings gathered from the creation of a multi-thematic virtual museum environment to be offered to visitors of real world museums. A number of design and implementation aspects are described along with an experiment designed to evaluate alternative approaches for implementing the navigation in a virtual museum environment. The paper is concluded with insights gained from the development of the virtual museum and portrays future research plans.

A Context-Based Adaptive Visualization Environment

Digital libraries and historical archives are increasingly employing visualization systems to facilitate the information retrieval and knowledge extraction tasks of their users. Typically, each organization employs a single visualization system, which may not suit best the needs of certain user groups, specific tasks, or properties of document collections to be visualized. In this paper, we present a context-based adaptive visualization environment, which embeds a set of visualization methods into a visualization library, from which the most appropriate one is selected for presenting information to the user. Methods are selected by examining parameters related to the user profile, system configuration and the set of data to be visualized, and employing a set of rules to assess the suitability of each method. The presented environment additionally monitors user behavior and preferences to adapt the visualization method selection criteria

Historical research in archives: user methodology and supporting tools

Historic research involves finding, using, and correlating information within primary and secondary sources, in order to communicate an understanding of past events. In this process, historians employ their scientific knowledge, experience, and intuition to formulate queries (who was involved in an event, when did an event occur etc.), and subsequently try to locate the pertinent information from their sources. In this article, the authors investigate how historians formulate queries, which query terms are chosen, and how historians proceed in searching for related information in sources. The insight gained from this investigation can be subsequently used for organizing documents within historical source repositories and building tools that will enable historians to access the needed information more rapidly and fully.

SPREADING ACTIVATION OVER ONTOLOGY-BASED RESOURCES: FROM PERSONAL CONTEXT TO WEB SCALE REASONING

This paper describes methods to allow spreading activation to be used on web-scale information resources. Existing work has shown that spreading activation can be used to model context over small personal ontologies, which can be used to assist in various user activities, for example, in auto-completing web forms. This previous work is extended and methods are developed by which large external repositories, including corporate information and the web, can be linked to the users personal ontology and thus allow automated assistance that is able to draw on the entire web of data. The basic idea is to augment the personal ontology with cached data from external repositories, where the choice of data to fetch or discard is related to the level of activation of entities already in the personal ontology or cached data. This relies on the assumption that the working set of highly active entities is relatively small; empirical results are presented, which suggest these assumptions are likely to hold. Implications of the techniques are discussed for user interaction and for the social web. In addition, warm world reasoning is proposed, applying rule-based reasoning over activated entities, potentially merging symbolic and sub-symbolic reasoning over web-scale knowledge bases.

Task-centred information management

The goal of DELOS Task 4.8 Task-centered Information Management is to provide the user with a Task-centered Information Management system (TIM), which automates users most frequent activities, by exploiting the collection of personal documents. In previous work we have explored the issue of managing personal data by enriching them with semantics according to a Personal Ontology, i.e. a user-tailored description of her domain of interest. Moreover, we have proposed a task specification language and a top-down approach to task inference, where the user specifies main aspects of the tasks using forms of declarative scripting. Recently, we have addressed new challenging issues related to TIM users task inference. More precisely, the first main contribution of this paper is the investigation of task inference theoretical issues. In particular, we show how the use of the Personal Ontology helps for computing simple task inference. The second contribution is an architecture for the system that implements simple task inference. In the current phase we are implementing a prototype for TIM whose architecture is the one presented in this paper.

Selected results of a comparative study of four ontology visualization methods for information retrieval tasks

The need for effective ontology visualization for design, management and browsing has arisen as a result of the progress in the areas of semantic Web and personal information management. There are several ontology visualizations available through existing ontology management tools, but not as many evaluations to determine their advantages and disadvantages and their suitability for various ontologies and user groups. This work presents selected results of an evaluation of four visualization methods in Protege.

Supporting Research in Historical Archives: Historical Information Visualization and Modeling Requirements

The on-going progress in the area of digital libraries has lead to the beginning of a digitization effort in Historical Archives, as well. The requirements of historical research, which works with histories of entities and incomplete information, create the need for supplementary tools to support users in handling the digitized content. This work is based on a user study of historian information retrieval methods in order to create a set of tools for the context of historical archives, which will facilitate historical data storage, management and visualization.

Evaluating the Significance of the Windows Explorer Visualization in Personal Information Management Browsing tasks

The visualization of hierarchies is very important for digital information management and presentation systems. Especially in the context of personal information management, file browsers play a very important role. Currently the most common file browser visualizations are windows explorer and the simple zoomable visualization offered by Microsoft windows. This work explores the issue of file browser visualization through a user study based on interviews and an experiment.