@conference {Rompa2011,
	title = {OntoFM: A Personal Ontology-based File Manager for the Desktop},
	booktitle = {Demo at the 10th International Web Conference, 2011, Bonn, Germany},
	year = {2011},
	month = {10},
	abstract = {OntoFM is a novel file manager that bases its interactivity on the user?s personal ontology, offering semantic browsing and searching mechanisms for locating files, a mind map inspired ontology visualization, and simple-to-use intuitive functionality that encourages less experienced users. The implementation of OntoFM is based on Protege, an extensible open source ontology editor and knowledge-base framework. The file manager is implemented as a Protege tab widget, retrieving information from your personal ontology. Ontology visualization is based upon the OntoGraf plug-in which has been extended to comply with the mind map paradigm. Currently the ontology visualization pane permits only navigational functions, while other ontology management functions have been hidden to ease the complexity of the user interface.},
	url = {https://arxiv.org/abs/1307.2018},
	author = {Rompa, J. and Giorgos Lepouras and Costas Vassilakis and Christos Tryfonopoulos}
}
@conference {560,
	title = {OntoFM: A Personal Ontology-based File Manager for the Desktop},
	booktitle = {Proccedings of the International Semantic Web Conference (ISWC)},
	year = {2011},
	month = {October},
	address = {Bonn, Germany},
	author = {Jenny Rompa and Giorgos Lepouras and Costas Vassilakis and Christos Tryfonopoulos}
}
@article {Katifori10a,
	title = {Ontologies and the brain: Using spreading activation through ontologies to support personal interaction},
	journal = {Cognitive Systems Research},
	volume = {Volume 11, Issue 1},
	year = {2010},
	note = {cited By (since 1996) 0; Article in Press},
	pages = {25-41},
	abstract = {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. Β{\textcopyright} 2009 Elsevier B.V.},
	doi = {10.1016/j.cogsys.2009.02.001},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-62249112875\&partnerID=40\&md5=7d25fb986738b4c71a627b3fec24c58d},
	author = {Akrivi Katifori and Costas Vassilakis and Alan Dix}
}
@conference {katifori2008e,
	title = {Ontologies as Tools for Historians},
	booktitle = {International Symposium on Information \& communication technologies in cultural heritage},
	year = {2008},
	month = {10},
	abstract = {Ontologies have been proven invaluable tools in areas like the semantic web and personal information management. There have been many research efforts to create ontologies and supporting tools for Natural Sciences and Biology in particular (e.g. the GO (http://www.geneontology.org/) ontology and supporting tools). However, the domain of History, the science of studying, recording and organizing the knowledge of the past, has yet to benefit from adopting ontologies. In this work, we present our findings in this area, focusing on the aspects of ontology modeling and ontology visualization.},
	author = {Akrivi Katifori and Costas Vassilakis}
}
@article {Katifori2007,
	title = {Ontology visualization methods - A survey},
	journal = {ACM Computing Surveys},
	volume = {39},
	number = {4},
	year = {2007},
	note = {cited By (since 1996) 21},
	pages = {10:1-10:43},
	abstract = {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. Β{\textcopyright} 2007 ACM.},
	keywords = {Digital libraries, Human computer interaction, Information management, Ontology, Ontology representation, Ontology visualization, Personalized information management, Semantic Web, visualization methods},
	doi = {10.1145/1287620.1287621},
	url = {http://www.scopus.com/inward/record.url?eid=2-s2.0-36048959880\&partnerID=40\&md5=a74cd76829bee9bb1cc21d6118e65340},
	author = {Akrivi Katifori and C. Halatsis and Giorgos Lepouras and Costas Vassilakis and E.G. Giannopoulou}
}
@conference {667640,
	title = {An Object-Oriented Approach for Designing Administrative E-forms and Transactional E-services},
	booktitle = {OOIS {\textquoteright}02: Proceedings of the 8th International Conference on Object-Oriented. Information Systems},
	year = {2002},
	month = {9},
	pages = {19{\textendash}30},
	publisher = {Springer-Verlag},
	organization = {Springer-Verlag},
	address = {London, UK},
	abstract = {Although electronic transaction services are considered to be a necessity for e-government, it has not been possible insofar to unleash their full potential. E-forms are central to the development of e-government, being a basic means for implementing the majority of the public services considered as required for local and central public administration authorities. In this paper, we present an object-oriented model for e-form-based administrative services, which spans the e-service lifecycle, including development, deployment and use by enterprises and citizens, data collection and communication with legacy information systems. The proposed approach encompasses semantic, structural and active aspects of e-forms, providing thus an inclusive framework for modelling electronic services.},
	isbn = {3-540-44087-9},
	doi = {10.1007/3-540-46102-7_6},
	author = {D. Gouscos and S. Rouvas and Costas Vassilakis and P. Georgiadis}
}
@article {Vassilakis200038,
	title = {An optimisation scheme for coalesce/valid time selection operator sequences},
	journal = {SIGMOD Record (ACM Special Interest Group on Management of Data)},
	volume = {29},
	number = {1},
	year = {2000},
	note = {cited By (since 1996) 4},
	pages = {38-43},
	abstract = {Queries in temporal databases often employ the coalesce operator, either to coalesce results of projections, or data which are not coalesced upon storage. Therefore, the performance and the optimisation schemes utilised for this operator is of major importance for the performance of temporal DBMSs. Insofar, performance studies for various algorithms that implement this operator have been conducted, however, the joint optimisation of the coalesce operator with other algebraic operators that appear in the query execution plan has only received minimal attention. In this paper, we propose a scheme for combining the coalesce operator with selection operators which are applied to the valid time of the tuples produced from a coalescing operation. The proposed scheme aims at reducing the number of tuples that a coalescing operator must process, while at the same time allows the optimiser to exploit temporal indices on the valid time of the data.},
	doi = {10.1145/344788.344803},
	url = {https://dl.acm.org/citation.cfm?id=344803},
	author = {Costas Vassilakis}
}
@conference {1990-hatzopoulos-delta,
	title = {An Object-Oriented Data Model for Hypermedia Systems},
	booktitle = {Proceedings of the DELTA Conference in Research and Development},
	year = {1990},
	month = {10},
	pages = {483{\textendash}493},
	abstract = {Hypermedia [1] is a fast growing field of research interest because of the new aspects introduced as far as it concerns the interaction between the machine and the user. The innovative features mainly refer to - the presence of various information types (multimedia environment) - the mapping of the semantic connections between information items into a flexible, efficient representation. This feature enables navigation through the information network in a meaningful way. Our effort concentrated on the definition and partial implementation of a flexible, general-purpose model through which the full capabilities of object-oriented programming can be exploited.},
	keywords = {databases},
	url = {http://cst.uop.gr/images/papers/1990-hatzopoulos-delta.pdf},
	author = {M. Hatzopoulos and D. Gouscos and M. Spiliopoulou and Costas Vassilakis and M. Vazirgiannis}
}
