@conference {826, title = {EnQuest: A Cloud Datalake Infrastructure for Heterogeneous Analytics in Maritime and Tourism Domains}, booktitle = {DATA 2023 (demo)}, year = {2023}, abstract = {

Within recent years, transportation and supply chain have been affected by an avalanche of data including IoT devices, online services, social media and others. However, the implemented solutions so far are fragmented, physically distributed, require specialized IT knowledge to deploy, and involve significant IT experience to operate even for trivial tasks. In the context of the ENIRISST+ project, we developed EnQuest1, an online data lake that allows users without any IT background to harvest, store, organize, analyze and share heterogeneous, multi-faceted maritime/tourism data. EnQuest provides a zero-administration, zero-cost, integrated framework that enables scientists, practitioners and other stakeholders within the above domains to easily: (i) deploy data acquisition services (crawlers, dataset imports, questionnaire forms), (ii) design and manage versatile customizable data stores, (iii) share whole datasets or horizontal/vertical data shards with other stakeholders, (iv) search, filter and analyze data via an expressive yet simple-to-use graphical query engine and visualization tools, and (v) perform user management and access control operations on the stored data. To the best of our knowledge, this is the first approach in the literature that targets users without an IT background and focuses on collecting, managing, analyzing, and sharing diverse, multi-faceted data in maritime the and tourism sectors. The main goals of the proposed demonstration are to showcase the EnQuest system to the conference participants and promote the work of the ENIRISST+ project consortium. During the demo we will (i) deploy social media crawlers to gather maritime data and show the participants how to process and visualise them, (ii) create live questionnaires using the EnQuest functionality, ask the participants to fill them in and demonstrate the live processed data on appropriate dashboards, and (iii) demonstrate how to import data and subscribe to data flows of other users through the implemented publish/subscribe module. For the needs of the demo we will only require internet connection and a desk; we will have our own laptops to use at the demonstration.

}, keywords = {big data, cloud systems, data analytics, datalakes, maritime, tourism}, author = {Kimon Deligiannis and Christos Tryfonopoulos and Paraskevi Raftopoulou and Nikos Platis and Costas Vassilakis} } @conference {821, title = {RoG: A Pipeline for Automated Sensitive Data Identification and Anonymisation}, booktitle = {Proceedings of the 2023 IEEE CSR Workshop on Data Science for Cyber Security (DS4CS)}, year = {2023}, abstract = {

Nowadays, the amount of data available online is constantly increasing. This data may contain sensitive or private information that can expose the person behind the data or be misused by malicious actors for identity theft, stalking, and other nefarious purposes. There is thus, a growing need to protect individuals{\textquoteright} privacy and prevent data breaches in several application domains. Protecting data privacy though, is a complex and multifaceted issue that involves a range of legal, ethical, and technical considerations. In this paper, we discuss the challenges associated with data protection, the role of automated tools, and the effectiveness of identifying and anonymising sensitive data. We then, propose a fully-automated process for sensitive data identification and anonymisation, based on Natural Language Processing (NLP) techniques, that can be applied both in big diverse datasets and to a wide range of domains.

}, keywords = {anonymisation, automated process, k-anonymity, NER, NLP, pipeline, sensitive/private data}, author = {Sotiris Nikoletos and Stefanos Vlachos and Efstathios Zaragkas and Costas Vassilakis and Christos Tryfonopoulos and Paraskevi Raftopoulou} } @conference {819, title = {SodaSense: An Intelligence Platform for Micro-Mobility, Micro-Climate and Agriculture}, booktitle = {Proceedings of the GEOProcessing 2023}, year = {2023}, abstract = {

SODASENSE is an end-to-end big data manipulation platform that focuses on decision and policy making. It concerns the management of big trajectory and spatio-temporal data that is collected from sensors and relates to micro-mobility, microclimate and agriculture, and aims to the creation of an expert decision making platform with research, social and business orientation.

}, keywords = {big data management and analysis, spatial time series, trajectories}, author = {Paraskevi Raftopoulou and Spiros Skiadopoulos and Christos Tryfonopoulos and Costas Vassilakis} } @article {772, title = {Hydria: An Online Data Lake for Multi-Faceted Analytics in the Cultural Heritage Domain}, journal = {Big Data and Cognitive Computing}, volume = {4}, year = {2020}, pages = {7}, abstract = {Advancements in cultural informatics have significantly influenced the way we perceive, analyze, communicate and understand culture. New data sources, such as social media, digitized cultural content, and Internet of Things (IoT) devices, have allowed us to enrich and customize the cultural experience, but at the same time have created an avalanche of new data that needs to be stored and appropriately managed in order to be of value. Although data management plays a central role in driving forward the cultural heritage domain, the solutions applied so far are fragmented, physically distributed, require specialized IT knowledge to deploy, and entail significant IT experience to operate even for trivial tasks. In this work, we present Hydria, an online data lake that allows users without any IT background to harvest, store, organize, analyze and share heterogeneous, multi-faceted cultural heritage data. Hydria provides a zero-administration, zero-cost, integrated framework that enables researchers, museum curators and other stakeholders within the cultural heritage domain to easily (i) deploy data acquisition services (like social media scrapers, focused web crawlers, dataset imports, questionnaire forms), (ii) design and manage versatile customizable data stores, (iii) share whole datasets or horizontal/vertical data shards with other stakeholders, (iv) search, filter and analyze data via an expressive yet simple-to-use graphical query engine and visualization tools, and (v) perform user management and access control operations on the stored data. To the best of our knowledge, this is the first solution in the literature that focuses on collecting, managing, analyzing, and sharing diverse, multi-faceted data in the cultural heritage domain and targets users without an IT background.}, keywords = {analytics and visualization, big data management, Cultural heritage, data lake, data store, open source}, doi = {10.3390/bdcc4020007}, url = {https://www.mdpi.com/2504-2289/4/2/7}, author = {Kimon Deligiannis and Paraskevi Raftopoulou and Christos Tryfonopoulos and Nikos Platis and Costas Vassilakis} } @article {589, title = {Efficient Continuous Multi-Query Processing over Graph Streams}, journal = {CoRR}, volume = {abs/1902.05134}, year = {2019}, url = {http://arxiv.org/abs/1902.05134}, author = {Lefteris Zervakis and Vinay Setty and Christos Tryfonopoulos and Katja Hose} } @conference {DBLP:conf/debs/ChantziosZST19, title = {Ping - A customizable, open-source information filtering system for textual data}, booktitle = {Proceedings of the 13th ACM International Conference on Distributed and Event-based Systems, DEBS 2019, Darmstadt, Germany, June 24-28, 2019.}, year = {2019}, pages = {228{\textendash}231}, doi = {10.1145/3328905.3332512}, url = {https://doi.org/10.1145/3328905.3332512}, author = {Thanasis Chantzios and Lefteris Zervakis and Spiros Skiadopoulos and Christos Tryfonopoulos} } @conference {588, title = {The quest for the appropriate cyber-threat intelligence sharing platform}, booktitle = {Proceedings of the 8th International Conference on Data Science, Technology and Applications (DATA), Prague, Czech Republic}, year = {2019}, month = { 07/2009}, abstract = {Cyber-threat intelligence (CTI) is any information that can help an organization identify, assess, monitor, and respond to cyber-threats. It relates to all cyber components of an organization such as networks, computers, and other types of information technology. In the recent years, due to the major increase of cyber-threats, CTI sharing is becoming increasingly important both as a subject of research and as a concept of providing additional security to organizations. However, selecting the proper tools and platforms for CTI sharing, is a challenging task, that pertains to a variety of aspects. In this paper, we start by overviewing the CTI procedure (threat types, categories, sources and the general CTI life-cycle). Then, we present a set of seven high-level CTI platform recommendations that can be used to evaluate a platform and subsequently we survey six state-of- the-art cyber-threat intelligence platforms. Finally, we compare and evaluate the six aforementioned platforms by means of the earlier proposed recommendations.}, keywords = {Cyber-threat, Intelligence, Sharing}, url = {http://users.uop.gr/~trifon/papers/pdf/data19-CKSKTBK.pdf}, author = {Thanasis Chantzios and Paris Koloveas and Spiros Skiadopoulos and Nikos Kolokotronis and Christos Tryfonopoulos and Vasiliki-Georgia Bilali and Dimitris Kavallieros} } @proceedings {590, title = {SciTo trends: visualising scientific topic trends}, year = {2019}, month = {September}, author = {Serafeim Chatzopoulos and Panagiotis Deligiannis and Thanasis Vergoulis and Ilias Kanellos and Christos Tryfonopoulos and Theodore Dalamagas} } @conference {545, title = {Data Science Tutor: An online platform for automated exercise solving in Data Science}, booktitle = {Proceedings of the 9th Conference on Computer Science Teaching (DIDINFO)}, year = {2018}, month = {October}, address = {Thessaloniki, Greece}, author = {Christos Tryfonopoulos and Charis Kotsiopoulos and Paraskevi Raftopoulou} } @conference {561, title = {The Effect of Introducing Content Price in Distributed Social Networks}, booktitle = {Proceedings of the 23rd Conference on Information Technologies (IT)}, year = {2018}, month = {March}, address = {Kaunas, Lithuania}, author = {Christos Tryfonopoulos} } @conference {578, title = {Efficient and Expressive Semantic Information Push for Cultural Heritage Applications}, booktitle = {Proceedings of the International Workshop on Semantic Web for Cultural Heritage (SW4CH @ ESWC)}, year = {2018}, month = {March}, address = {Crete, Greece}, author = {Christos Tryfonopoulos} } @conference {558, title = {A Methodology for the Automatic Creation of Massive Continuous Query Datasets from Real-Life Corpora}, booktitle = {Proceedings of the 7th International Conference on Advanced Computer Science and Information Technology (ICAIT)}, year = {2018}, month = {April}, address = {Vienna, Austria}, author = {Christos Tryfonopoulos} } @article {581, title = {Query Reorganisation Algorithms for Efficient Boolean Information Filtering}, journal = {IEEE Transactions on Knowledge and Data Engineering}, volume = {29}, year = {2017}, pages = {418{\textendash}432}, abstract = {In the information filtering paradigm, clients subscribe to a server with continuous queries that express their information needs and get notified every time appropriate information is published. To perform this task in an efficient way, servers employ indexing schemes that support fast matches of the incoming information with the query database. Such indexing schemes involve (i) main-memory trie-based data structures that cluster similar queries by capturing common elements between them and (ii) efficient filtering mechanisms that exploit this clustering to achieve high throughput and low filtering times. However, state-of-the-art indexing schemes are sensitive to the query insertion order and cannot adopt to an evolving query workload, degrading the filtering performance over time. In this paper, we present an adaptive trie-based algorithm that outperforms current methods by relying on query statistics to reorganise the query database. Contrary to previous approaches, we show that the nature of the constructed tries, rather than their compactness, is the determining factor for efficient filtering performance. Our algorithm does not depend on the order of insertion of queries in the database, manages to cluster queries even when clustering possibilities are limited, and achieves more than 96\% filtering time improvement over its state-of-the-art competitors. Finally, we demonstrate that our solution is easily extensible to multi-core machines.}, keywords = {dissemination, indexing methods, Information filtering, user profiles and alert services}, doi = {10.1109/TKDE.2016.2620140}, url = {https://doi.org/10.1109/TKDE.2016.2620140}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Spiros Skiadopoulos and Manolis Koubarakis} } @conference {591, title = {A crawler architecture for harvesting the clear, social, and dark web for IoT-related cyber-threat intelligence}, booktitle = {In Proceedings of the IEEE Workshop on Cyber Security \& Resilience in the Internet of Things (CSRIoT @ IEEE Services)}, year = {2016}, month = {July 2016}, publisher = {IEEE}, organization = {IEEE}, address = {Milan, Italy}, abstract = {The clear, social, and dark web have lately been identified as rich sources of valuable cyber-security information that {\textendash}given the appropriate tools and methods{\textendash} may be identified, crawled and subsequently leveraged to actionable cyber- threat intelligence. In this work, we focus on the information gathering task, and present a novel crawling architecture for transparently harvesting data from security websites in the clear web, security forums in the social web, and hacker fo- rums/marketplaces in the dark web. The proposed architecture adopts a two-phase approach to data harvesting. Initially a machine learning-based crawler is used to direct the harvesting towards websites of interest, while in the second phase state- of-the-art statistical language modelling techniques are used to represent the harvested information in a latent low-dimensional feature space and rank it based on its potential relevance to the task at hand. The proposed architecture is realised using exclusively open-source tools, and a preliminary evaluation with crowdsourced results demonstrates its effectiveness.}, keywords = {crawling architecture, cyber-security, cyber-threat intelligence, IoT, language models, Machine Learning}, url = {http://users.uop.gr/ trifon/papers/pdf/csriot19-KCTS.pdf}, author = {Paris Koloveas and Thanasis Chantzios and Christos Tryfonopoulos and Spiros Skiadopoulos} } @conference {DBLP:conf/esws/ZervakisTSK16, title = {Full-Text Support for Publish/Subscribe Ontology Systems}, booktitle = {The Semantic Web. Latest Advances and New Domains - 13th International Conference, ESWC 2016, Heraklion, Crete, Greece, May 29 - June 2, 2016, Proceedings}, year = {2016}, pages = {233{\textendash}249}, doi = {10.1007/978-3-319-34129-3_15}, url = {https://doi.org/10.1007/978-3-319-34129-3_15}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Spiros Skiadopoulos and Manolis Koubarakis} } @conference {575, title = {R-Susceptibility: An IR-Centric Approach to Assessing Privacy Risks for Users in Online Communities}, booktitle = {Proceedings of the 39th Annual International ACM SIGIR Conference}, year = {2016}, month = {July}, address = {Pisa, Italy}, author = {Joanna Asia Biega and Krishna P. Gummadi and Ida Mele and Dragan Milchevski and Christos Tryfonopoulos and Gerhard Weikum} } @conference {DBLP:conf/edbt/ZervakisTSSS16, title = {Towards Publish/Subscribe Functionality on Graphs}, booktitle = {Proceedings of the Workshops of the EDBT/ICDT 2016 Joint Conference, EDBT/ICDT Workshops 2016, Bordeaux, France, March 15, 2016.}, year = {2016}, url = {http://ceur-ws.org/Vol-1558/paper13.pdf}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Vinay Setty and Stephan Seufert and Spiros Skiadopoulos} } @conference {DBLP:conf/kcap/TsafaraTSZ15, title = {Cloud-Based Data and Knowledge Management for Multi-Centre Biomedical Studies}, booktitle = {Proceedings of the 8th International Conference on Knowledge Capture, K-CAP 2015, Palisades, NY, USA, October 7-10, 2015}, year = {2015}, pages = {24:1{\textendash}24:4}, doi = {10.1145/2815833.2816949}, url = {https://doi.org/10.1145/2815833.2816949}, author = {Amalia Tsafara and Christos Tryfonopoulos and Spiros Skiadopoulos and Lefteris Zervakis} } @conference {563, title = {Cloud-Based Data and Knowledge Management for Multi-Centre Biomedical Studies}, booktitle = {Proceedings of the International Conference on Knowledge Capture (K-CAP)}, year = {2015}, month = {October 7-10}, address = {Palisades NY, USA}, abstract = {Among the basic research tools for (bio)medical science are epidemiological studies that typically involve a number of hospitals, clinics, and research centres scattered around the world, and are often referred to as multi-centre studies. Clearly, the effectiveness and importance of a multi-centre study increases with the number of participating centres and enrolled patients, but at the same time this natural distribution in the production of research data requires sophisticated data management infrastructures to support the participating units. This kind of infrastructure is not only expensive to build and maintain, but also cannot be reused as it is often tailored to a specific study. In this work, we present a cloud-based system, coined CLOUDSTUDY, that allows users without any computer science background to design, deploy, and administer platforms aimed for managing, sharing, and analysing clinical data from multi-centre studies. The CLOUDSTUDY system provides a zero-administration, zero-cost online tool for creating multi- centre studies that (i) enhances re-usability by introducing study templates, (ii) supports (bio)medical needs through specialised data types, and (iii) emphasises data filtering/export through an expressive yet simple graphical query engine.}, doi = {10.1145/2815833.2816949}, url = {https://doi.org/10.1145/2815833.2816949}, author = {Amalia Tsafara and Christos Tryfonopoulos and Spiros Skiadopoulos and Lefteris Zervakis} } @conference {570, title = {Constructing Subsumption Hierarchies of Web Queries}, booktitle = {Proceedings of the International Workshop on Dataset PROFIling and fEderated Search for Linked Data (PROFILES @ ESWC)}, year = {2015}, month = {May}, address = {Portoroz, Slovenia}, author = {Alexander Prohaska and Christos Tryfonopoulos and Georgiana Ifrim} } @conference {kmas15, title = {A mobile-enabled platform for presenting and disseminating cultural heritage information enhanced with augmented reality (Greek title: ΜΙΑ ΠΛΑΤΦΟΡΜΑ ΓΙΑ ΠΑΡΟΥΣΙΑΣΗ ΚΑΙ ΔΙΑΧΥΣΗ ΠΛΗΡΟΦΟΡΙΩΝ ΠΟΛΙΤΙΣΤΙΚΗΣ ΚΛΗΡΟΝΟΜΙΑΣ ΜΕ ΥΠΟΣΤΗΡΙΞΗ ΓΙΑ ΚΙΝΗΤΕΣ ΣΥΣΚΕΥΕΣ ΚΑΙ ΕΜΠ}, booktitle = {1st Panhellenic Conference on Cultural Heritage Digitization}, year = {2015}, month = {9}, abstract = {The advent of mobile technologies has created opportunities for more effective delivery of cultural heritage information to all interested parties, and especially tourists who are on-the-move. Many people nowadays are equipped with smartphones or tablets equipped with location tracking devices such as GPS and compasses and having internet access available; these smartphones can be used for efficient delivery of cultural heritage information, in a personalized and timely fashion. Moreover, the computing resources of these smartphones are adequate to enable the use of augmented reality techniques, which provide a lively and engaging experience to the users. However, the same content still needs to be disseminated to users of stationary computers. In this paper, we report on the design and development of a mobile-enabled platform for presenting and disseminating cultural heritage information enhanced with augmented reality and integration with social networks.}, author = {K. Μασσέλος and Costas Vassilakis and Giorgos Lepouras and Christos Tryfonopoulos and Ν. Τσελίκας and Nikos Platis} } @conference {556, title = {A Platform for the Presentation and Dissemination of Cultural Heritage Information for Mobile Devices Enriched with Augmented Reality}, booktitle = {Proceedings of the Greek Conference for the Digitization of Cultural Information (EUROMED)}, year = {2015}, month = {September}, address = {Volos, Greece}, author = {K. Masselos and Costas Vassilakis and Giorgos Lepouras and Christos Tryfonopoulos and N. Tselikas and N. Platis} } @conference {aamas15-GPT, title = {PViz: Visualising P2P Multi-Agent Simulations}, booktitle = {Proceedings of the International Conference on Autonomous Agents and Multiagent Systems (AAMAS)}, year = {2015}, month = {May}, pages = {1945{\textendash}1946}, address = {Istanbul, Turkey}, author = {Dimitris Giouroukis and Nikos Platis and Christos Tryfonopoulos} } @inbook {565, title = {SECRETA: A Tool for Anonymizing Relational, Transaction and RT-Datasets}, booktitle = {Medical Data Privacy Handbook}, year = {2015}, pages = {83-109}, publisher = {Springer}, organization = {Springer}, author = {Giorgos Poulis and Aris Gkoulalas-Divanis and Grigorios Loukides and Spiros Skiadopoulos and Christos Tryfonopoulos}, editor = {Aris Gkoulalas-Divanis and Grigorios Loukides} } @inbook {DBLP:books/sp/15/PoulisGLST15, title = {SECRETA: A Tool for Anonymizing Relational, Transaction and RT-Datasets}, booktitle = {Medical Data Privacy Handbook}, year = {2015}, pages = {83{\textendash}109}, doi = {10.1007/978-3-319-23633-9_5}, url = {https://doi.org/10.1007/978-3-319-23633-9_5}, author = {Giorgos Poulis and Aris Gkoulalas-Divanis and Grigorios Loukides and Spiros Skiadopoulos and Christos Tryfonopoulos} } @conference {541, title = {Towards Content-Based Publish/Subscribe for Distributed Social Networks}, booktitle = {Proceedings of the International Conference on Distributed Event-Based Systems (DEBS)}, year = {2015}, month = {June}, address = {Oslo, Norway}, author = {Christos Tryfonopoulos and Paraskevi Raftopoulou and Vinay Setty and Argiris Xiros} } @article {582, title = {Distributed Large-Scale Information Filtering}, journal = {Transactions on Large-Scale Data- and Knowledge-Centered Systems (TLDKS)}, volume = {13}, year = {2014}, pages = {91{\textendash}122}, abstract = {We study the problem of distributed resource sharing in peer-to-peer networks and focus on the problem of information filter- ing. In our setting, subscriptions and publications are specified using an expressive attribute-value representation that supports both the Boolean and Vector Space models. We use an extension of the distributed hash table Chord to organise the nodes and store user subscriptions, and utilise efficient publication protocols that keep the network traffic and latency low at filtering time. To verify our approach, we evaluate the proposed protocols experimentally using thousands of nodes, millions of user subscriptions, and two different real-life corpora. We also study three important facets of the load-balancing problem in such a scenario and present a novel algorithm that manages to distribute the load evenly among the nodes. Our results show that the designed protocols are scalable and efficient: they achieve expressive information filtering functionality with low message traffic and latency.}, keywords = {distributed hash tables, Information management, publish/subscribe}, author = {Christos Tryfonopoulos and Stratos Idreos and Manolis Koubarakis and Paraskevi Raftopoulou} } @conference {553, title = {Mindmap-Inspired Semantic Personal Information Management}, booktitle = {Proceedings of the 17th International Conference on Extending Database Technology (EDBT)}, year = {2014}, month = {March}, address = {Athens, Greece}, author = {Jenny Rompa and Christos Tryfonopoulos and Costas Vassilakis and Giorgos Lepouras} } @conference {Rompa2014, title = {Mindmap-Inspired Semantic Personal Information Management}, booktitle = {Demo at the 17th International Conference on Extending Database Technology, 2014, Athens, Greece}, year = {2014}, month = {3/2014}, abstract = {Users nowadays need to manage large amounts of information, including documents, e-mails, contacts, and multimedia content. To facilitate the tasks of organisation, maintenance, and retrieval of personal information, a number of semantics-based methods have emerged; these methods employ (personal) ontologies as an underlying infrastructure for organising and querying the personal information space. In this paper we present OntoFM, a novel personal information management tool that offers a mindmap-inspired interface to facilitate user interactions with the information base. Besides serving as an information retrieval aid, OntoFM allows the user to specify and update the semantic links between information items, constituting thus a complete personal information management tool.}, doi = {10.5441/002/edbt.2014.55}, url = {http://dx.doi.org/10.5441/002/edbt.2014.55}, author = {Rompa, J. and Christos Tryfonopoulos and Costas Vassilakis and Giorgos Lepouras} } @conference {DBLP:conf/edbt/PoulisGLST14, title = {SECRETA: A System for Evaluating and Comparing RElational and Transaction Anonymization algorithms}, booktitle = {Proceedings of the 17th International Conference on Extending Database Technology, EDBT 2014, Athens, Greece}, year = {2014}, month = {March 24-28}, pages = {620{\textendash}623}, doi = {10.5441/002/edbt.2014.58}, url = {https://doi.org/10.5441/002/edbt.2014.58}, author = {Giorgos Poulis and Aris Gkoulalas-Divanis and Grigorios Loukides and Spiros Skiadopoulos and Christos Tryfonopoulos} } @conference {DBLP:conf/bibe/TsafaraTS13, title = {CloudStudy: A cloud-based system for supporting multi-centre studies}, booktitle = {13th IEEE International Conference on BioInformatics and BioEngineering, BIBE 2013, Chania, Greece, November 10-13, 2013}, year = {2013}, pages = {1{\textendash}4}, doi = {10.1109/BIBE.2013.6701549}, url = {https://doi.org/10.1109/BIBE.2013.6701549}, author = {Amalia Tsafara and Christos Tryfonopoulos and Spiros Skiadopoulos} } @conference {550, title = {DS4: A Distributed Social and Semantic Search System}, booktitle = {Proceedings of 35th European Conference on Information Retrieval (ECIR)}, year = {2013}, month = {March}, address = {Moscow, Russia}, author = {Dionisis Kontominas and Paraskevi Raftopoulou and Christos Tryfonopoulos and E.G.M. Petrakis} } @conference {539, title = {DS4: Introducing Semantic Friendship in Distributed Social Networks.}, booktitle = {Proceedings of the 21st International Conference on Cooperative Information Systems (CoopIS)}, year = {2013}, month = {September}, address = {Graz, Austria}, author = {Paraskevi Raftopoulou and Christos Tryfonopoulos and E.G.M. Petrakis and Nikos Zevlis} } @article {DBLP:journals/corr/ZervakisTPKS13, title = {Full-text Support for Publish/Subscribe Ontology Systems}, journal = {CoRR}, volume = {abs/1307.2015}, year = {2013}, url = {http://arxiv.org/abs/1307.2015}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Antonios Papadakis-Pesaresi and Manolis Koubarakis and Spiros Skiadopoulos} } @conference {554, title = {Full-text Support for Publish/Subscribe Ontology Systems}, booktitle = {Proceedings of the Extended Semantic Web Conference (ESWC)}, year = {2012}, month = {May}, address = {Crete, Greece}, author = {Lefteris Zervakis and Christos Tryfonopoulos and Antonios Papadakis-Pesaresi and Manolis Koubarakis and Spiros Skiadopoulos} } @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} } @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 {538, title = {Pricing Information Goods in Distributed Agent-based Information Filtering}, booktitle = {Proceedings of the 19th International Conference on Cooperative Information Systems (CoopIS)}, year = {2011}, month = {October}, address = {Crete, Greece}, author = {Christos Tryfonopoulos and Laura Maria Andreescu} } @conference {537, title = {Anonymity and Censorship Resistance in Unstructured Overlay Networks}, booktitle = {Proceedings of the 17th International Conference on Cooperative Information Systems (CoopIS)}, year = {2009}, month = {November}, address = {Vilamoura, Portugal}, author = {Michael Backes and Marek Hamerlik and Alessandro Linari and Matteo Maffei and Christos Tryfonopoulos and Gerhard Weikum} } @conference {562, title = {EverLast: A Distributed Architecture for Preserving the Web}, booktitle = {Proceedings of the Joint Conference on Digital Libraries (JCDL)}, year = {2009}, month = {June}, address = {Austin, Texas}, author = {Avishek Anand and Srikanta Bedathur and Klaus Berberich and Ralf Schenkel and Christos Tryfonopoulos} } @article {583, title = {Information Filtering and Query Indexing for an Information Retrieval Model}, journal = {ACM Transactions on Information Systems (TOIS)}, volume = {27}, year = {2009}, pages = {1{\textendash}47}, author = {Christos Tryfonopoulos and Manolis Koubarakis and Yannis Drougas} } @article {540, title = {Rewiring Strategies for Semantic Overlay Networks}, journal = {Distributed and Parallel Databases (DAPD)}, volume = {26}, year = {2009}, pages = {181{\textendash}205}, abstract = {Semantic overlay networks cluster peers that are semantically, thematically or socially close into groups, by means of a rewiring procedure that is periodically executed by each peer. This procedure establishes new connections to similar peers and disregards connections to peers that are dissimilar. Retrieval effectiveness is then improved by exploiting this information at query time (as queries may address clusters of similar peers). Although all systems based on semantic overlay networks apply some rewiring technique, there is no comprehensive study showing the effect of rewiring on system{\textquoteright}s performance. In this work, a framework for studying the attribution of rewiring strategies in semantic overlay networks is proposed. A generic approach to rewiring is presented and several variants of this approach are reviewed and evaluated. We show how peer organisation is affected by the different design choices of the rewiring mechanism and how these choices affect the performance of the system overall (both in terms of communication overhead and retrieval effectiveness). Our experimental evaluation with real-word data and queries confirms the dependence between rewiring strategies and retrieval performance, and gives insights on the trade-offs involved in the selection of a rewiring strategy.}, keywords = {Information retrieval, peer-to-peer networks, rewiring strategies, semantic overlay networks}, author = {Paraskevi Raftopoulou and E.G.M. Petrakis and Christos Tryfonopoulos} } @booklet {569, title = {Anonymous and Censorship-resistant Content-sharing in Unstructured Overlays}, year = {2008}, author = {Michael Backes and Marek Hamerlik and Alessandro Linari and Matteo Maffei and Christos Tryfonopoulos and Gerhard Weikum} } @conference {586, title = {Approximate Information Filtering in Peer-to-Peer Networks}, booktitle = {Proceedings of the 9th Web Information Systems Engineering (WISE) Conference}, year = {2008}, month = {September}, address = {Auckland, New Zealand}, author = {Christian Zimmer and Christos Tryfonopoulos and Klaus Berberich and Manolis Koubarakis and Gerhard Weikum} } @conference {574, title = {Exploiting Correlated Keywords to Improve Approximate Information Filtering}, booktitle = {Proceedings of the 31st Annual International ACM SIGIR Conference}, year = {2008}, month = {July}, address = {Singapore}, author = {Christian Zimmer and Christos Tryfonopoulos and Gerhard Weikum} } @conference {549, title = {Information Retrieval and Filtering over Self-Organising Digital Libraries}, booktitle = {Proceedings of the 12th European Conference on Research and Advanced Technology for Digital Libraries (ECDL)}, year = {2008}, month = {September}, address = {Aarhus, Denmark}, author = {Paraskevi Raftopoulou and E.G.M. Petrakis and Christos Tryfonopoulos and Gerhard Weikum} } @conference {566, title = {P2P Information Retrieval and Filtering with MAPS}, booktitle = {Proccedings of the IEEE International Conference on Peer-to-Peer Computing (P2P)}, year = {2008}, month = {September}, address = {Aachen, Germany}, author = {Christian Zimmer and Johannes Heinz and Christos Tryfonopoulos and Gerhard Weikum} } @article {557, title = {Architectural Alternatives for Information Filtering in Structured Overlay Networks}, journal = {IEEE Internet Computing}, volume = {11}, year = {2007}, pages = {24-34}, author = {Christos Tryfonopoulos and Christian Zimmer and Manolis Koubarakis and Gerhard Weikum} } @conference {543, title = {Efficient Search and Approximate Information Filtering in a Distributed Peer-to-Peer Environment of Digital Libraries}, booktitle = {Proceedings of the DELOS Conference on Digital Libraries}, year = {2007}, month = {February}, address = {Pisa, Italy}, author = {Christian Zimmer and Christos Tryfonopoulos and Gerhard Weikum} } @conference {548, title = {MinervaDL: An Architecture for Information Retrieval and Filtering in Distributed Digital Libraries}, booktitle = {Proceedings of the 11th European Conference on Research and Advanced Technology for Digital Libraries (ECDL)}, year = {2007}, month = {September}, address = {Budapest, Hungary}, author = {Christian Zimmer and Christos Tryfonopoulos and Gerhard Weikum} } @conference {564, title = {Node Behavior Prediction for Large-Scale Approximate Information Filtering}, booktitle = {Proceedings of the International Workshop on Large-Scale Distributed Systems for Information Retrieval (LSDS-IR @ SIGIR)}, year = {2007}, month = {July}, address = {Amsterdam, The Netherlands}, author = {Christian Zimmer and Christos Tryfonopoulos and Klaus Berberich and Gerhard Weikum and Manolis Koubarakis} } @conference {559, title = {Distributed Evaluation of Continuous Equi-join Queries over Large Structured Overlay Networks}, booktitle = {Proceedings of the 22nd International Conference on Data Engineering (ICDE)}, year = {2006}, month = {April}, address = {Atlanda, USA}, author = {Stratos Idreos and Christos Tryfonopoulos and Manolis Koubarakis} } @article {DBLP:journals/tkde/KoubarakisST06, title = {Logic and Computational Complexity for Boolean Information Retrieval}, journal = {IEEE Trans. Knowl. Data Eng.}, volume = {18}, number = {12}, year = {2006}, pages = {1659{\textendash}1666}, doi = {10.1109/TKDE.2006.193}, url = {https://doi.org/10.1109/TKDE.2006.193}, author = {Manolis Koubarakis and Spiros Skiadopoulos and Christos Tryfonopoulos} } @conference {adpuc06-BKTWZ, title = {MAPS: Approximate Publish/Subscribe Functionality in Peer-to-Peer Networks}, booktitle = {Proceedings of Advanced Data Processing in Ubiquitous Computing Workshop (ADPUC @ Middleware)}, year = {2006}, month = {November}, pages = {1{\textendash}6}, address = {Melbourne, Australia}, author = {Klaus Berberich and Manolis Koubarakis and Christos Tryfonopoulos and Gerhard Weikum and Christian Zimmer} } @conference {547, title = {LibraRing: An Architecture for Distributed Digital Libraries Based on DHTs}, booktitle = {Proceedings of the 9th European Conference on Research and Advanced Technology for Digital Libraries (ECDL)}, year = {2005}, month = {September}, address = {Vienna, Austria}, author = {Christos Tryfonopoulos and Stratos Idreos and Manolis Koubarakis} } @conference {542, title = {Publish/Subscribe Functionalities for Future Digital Libraries using Structured Overlay Networks}, booktitle = {Proceedings of the 8th International Workshop of the DELOS Network of Excellence on Digital Libraries on Future Digital Library Management Systems}, year = {2005}, month = {March}, address = {Schloss Dagstuhl, Germany}, author = {Christos Tryfonopoulos and Stratos Idreos and Manolis Koubarakis} } @conference {573, title = {Publish/Subscribe Functionality in IR Environments using Structured Overlay Networks}, booktitle = {Proceedings of the 28th Annual International ACM SIGIR Conference}, year = {2005}, month = {August}, address = {Salvador, Brazil}, author = {Christos Tryfonopoulos and Stratos Idreos and Manolis Koubarakis} } @conference {571, title = {Distributed Resource Sharing using Self-Organized Peer-to-Peer Networks and Languages from Information Retrieval}, booktitle = {Proceedings of the International Workshop on Self-* Properties in Complex Information Systems (Self-*)}, year = {2004}, month = {May}, address = {Bertinoro, Italy}, author = {Christos Tryfonopoulos and Manolis Koubarakis} } @conference {568, title = {Implementing Publish/Subscribe Systems with Languages from Information Retrieval on Top of Structured Overlay Networks}, booktitle = {Proceedings of the International Workshop on Peer-to-Peer and IR (P2P\&IR @ SIGIR)}, year = {2004}, month = {July}, address = {Sheffield, UK}, author = {Christos Tryfonopoulos and Manolis Koubarakis} } @conference {576, title = {P2P-DIET: An Extensible P2P Service that Unifies Ad-hoc and Continuous Querying in Super-Peer Networks}, booktitle = {Proceedings of the ACM SIGMOD Conference}, year = {2004}, month = {June}, address = {Paris, France}, author = {Stratos Idreos and Manolis Koubarakis and Christos Tryfonopoulos} } @conference {551, title = {P2P-DIET: One-Time and Continuous Queries in Super-Peer Networks}, booktitle = {Proceedings of the 9th International Conference on Extending Database Technology (EDBT)}, year = {2004}, month = {March}, address = {Heraklion, Greece}, author = {Stratos Idreos and Manolis Koubarakis and Christos Tryfonopoulos} } @conference {585, title = {Publish/Subscribe Systems with Distributed Hash Tables and Languages from Information Retrieval}, booktitle = {Proceedings of the 6th Workshop on Distributed Data and Structures (WDAS)}, year = {2004}, month = {July}, address = {Lausanne, Switzerland}, author = {Christos Tryfonopoulos and Manolis Koubarakis} } @conference {567, title = {Query Processing in Super-Peer Networks with Languages Based on Information Retrieval: the P2P-DIET Approach}, booktitle = {Proceedings of the International Workshop on Peer-to-peer Computing and Databases (P2P\&DB @ EDBT)}, year = {2004}, month = {March}, address = {Herakion, Greece}, author = {Stratos Idreos and Christos Tryfonopoulos and Manolis Koubarakis and Yannis Drougas} } @article {577, title = {Selective Information Dissemination in P2P Networks: Problems and Solutions}, journal = {SIGMOD Record, Special Issue on Peer-to-Peer Data Management}, volume = {32}, year = {2003}, pages = {71-76}, author = {Manolis Koubarakis and Christos Tryfonopoulos and Stratos Idreos and Yannis Drougas}, editor = {Karl Aberer} } @conference {536, title = {Data Models and Languages for Agent-Based Textual Information Dissemination}, booktitle = {Proceedings of the 6th International Workshop on Cooperative Information Agents (CIA)}, year = {2002}, month = {September}, publisher = {Springer}, organization = {Springer}, address = {Madrid, Spain}, author = {Manolis Koubarakis and Christos Tryfonopoulos and Paraskevi Raftopoulou and Theodoros Koutris} } @conference {572, title = {Efficient Agent-Based Dissemination of Textual Information}, booktitle = {Proceedings of the 2nd Hellenic Conference on Artificial Intelligence (SETN)}, year = {2002}, month = {April}, address = {Thessaloniki, Greece}, author = {Manolis Koubarakis and Theodoros Koutris and Paraskevi Raftopoulou and Christos Tryfonopoulos} } @conference {546, title = {Information Alert in Distributed Digital Libraries: The Models, Languages, and Architecture of DIAS}, booktitle = {Proceedings of the 6th European Conference on Research and Advanced Technology for Digital Libraries (ECDL)}, year = {2002}, month = {September}, address = {Rome, Italy}, author = {Manolis Koubarakis and Theodoros Koutris and Christos Tryfonopoulos and Paraskevi Raftopoulou} } @conference {584, title = {Peer-to-peer Agent Systems for Textual Information Dissemination: Algorithms and Complexity}, booktitle = {Proceedings of the UK Workshop on Multiagent Systems (UKMAS)}, year = {2002}, month = {December}, address = {Liverpool, UK}, author = {Manolis Koubarakis and Christos Tryfonopoulos} } @conference {599, title = {Agents in Decentralised Information Ecosystems: The DIET Approach}, booktitle = {Symposium on Information Agents for E-Commerce, AISB Convention}, year = {2001}, month = {March}, address = {University of York, United Kingdom}, abstract = {The complexity of the current global information infrastructure requires novel means of understanding and exploiting the dynamics of information. One means may be through the concept of an information ecosystem. An information ecosystem is analogous to a natural ecosystem in which there are flows of materials and energy analogous to information flow between many interacting individuals. This paper describes a multi-agent platform, DIET (Decentralised Information Ecosystem Technologies) that can be used to implement open, robust, adaptive and scalable ecosystem-inspired systems. We describe the design principles of the DIET software architecture, and present a simple example application based upon it. We go on to consider how the DIET system can be used to develop information brokering agents, and how these can contribute to the implementation of economic interactions between agents, as well as identifying some open questions relating to research in these areas. In this way we show the capacity of the DIET system to support applications using information agents.}, author = {P. Marrow and Manolis Koubarakis and R.H. van Lengen and F. Valverde-Albacete and E. Bonsma and J. Cid-Suerio and A.R. Figueiras-Vidal and A. Gallardo-Antolin and C. Hoile and T. Koutris and H. Molina-Bulla and A. Navia-Vazquez and Paraskevi Raftopoulou and N. Skarmeas and Christos Tryfonopoulos and F. Wang and C. Xiruhaki} } @conference {aisb01-MKL+, title = {Agents in Decentralised Information Ecosystems: The DIET Approach}, booktitle = {Proccedings of the Symposium on Information Agents for E-Commerce, AISB Convention}, year = {2001}, month = {March}, pages = {109{\textendash}117}, address = {York, UK}, author = {P. Marrow and Manolis Koubarakis and R.H. van Lengen and F. Valverde-Albacete and E. Bonsma and J. Cid-Suerio and A.R. Figueiras-Vidal and A. Gallardo-Antolin and C. Hoile and T. Koutris and H. Molina-Bulla and A. Navia-Vazquez and Paraskevi Raftopoulou and N. Skarmeas and Christos Tryfonopoulos and F. Wang and C. Xiruhaki} }