Christoph Lofi

PLEASE FIND MY NEW WEB PAGE HERE

 

Assistant Professor at the Web Information Systems group of the Faculty of Engineering, Mathematics and Computer Science (EEMCS/EWI), Delft University of Technology.

My research is on Semantics-based Data Engineering methods and techniques. The general problem in data engineering is that the source data available to a data-driven system is often not fit for that purpose because data is scattered between different sources, is of low quality, or important semantic information is only implicitly available. This is a central challenge in the arising data-driven economy and a major detrimental aspect in many AI- or Data Science-driven systems. Data processing pipelines are needed to overcome these issues, producing the required target data from the available source data.

In the context of this challenge, I focus on problem scenarios where there is a semantic mismatch between mostly unstructured source data and structured target data. My research enables the engineering of sophisticated data processing pipelines for these scenarios which can tackle non-trivial issues with respect to integrating data from different sources, transforming data to more suitable granularities or more explicit representations, and augmenting data with additional data points and properties. This is a challenging aspect of data engineering, and solutions rely on recent methods for facilitating semantic enrichment like natural language processing, information extraction, crowd computing, or AI-driven data analysis.    

I chose several application domains for validating my research, focusing on domains where data produced by humans needs to be analyzed and processed. These domains typically exhibit a strong semantic and structural mismatch between available and desired data, and thus are effective testing grounds for my research. Examples are digital libraries and enterprise digital text repositories, online education information systems, and information systems for supporting digital humanities research.

Short CV

2016: Assistant Professor Delft University of Technology
2014-2016: PostDoc at Technische Universität Braunschweig
2012-2014: PostDoc at National Institute of Informatics, Tokyo, Japan
2011-2012: PostDoc at Technische Universität Braunschweig
2011: Defense of Doctoral Thesis at Technische Universität Braunschweig
2008-2011: Ph.D. Researcher at Technische Universität Braunschweig
2006-2008: Ph.D. Researcher at L3S Research Center, Leibniz University Hannover
2005: Diploma Thesis at Collaborative Software Development Laboratory, University of Hawai’i, Honolulu - Manoa, Certificate issued by University Kaiserslautern
2002-2004: Assistant Researcher at Fraunhofer Institute for Experimental Software Engineering, Kaiserslautern 
2000-2004: Student at University Kaiserslautern

Publications

2021

Agathe Balayn, Panagiotis Soilis, Christoph Lofi, Jie Yang, and Alessandro Bozzon. "What do You Mean? Interpreting Image Classification with Crowdsourced Concept Extraction and Analysis". In The Web Conference (WWW). 2021. PDF.

Christos Koutras, George Siachamis, Andra Ionescu, Kyriakos Psarakis, Jerry Brons, Marios Fragkoulis, Christoph Lofi, Angela Bonifati, and Asterios Katsidodimos. "Valentine: Evaluating Matching Techniques for Dataset Discovery". In Int. Conf. on Data Engineering (ICDE). 2021. PDF.

Agathe Balayn, Christoph Lofi, and Geert-Jan Houben. "Managing bias and unfairness in data for decision support: a survey of machine learning and data engineering approaches to identify and mitigate bias and unfairness within data management and analytics systems". The VLDB Journal, 2021. PDF, DOI.

Ionnis Petros Samiotis, Christoph Lofi, and Alessandro Bozzon. "Hybrid Annotation Systems for Music Transcription". In Int. Workshop on Reading Music Systems. 2021. PDF.

2020

Tom Harting, Sepideh Mesbah, and Christoph Lofi. "LOREM: Language-consistent Open Relation Extraction from Unstructured Text". In The Web Conference (WWW). Taipei, Taiwan, apr 2020. PDF.

Christos Koutras, Marios Fragkoulis, Asterios Katsifodimos, and Christoph Lofi. "REMA: Graph Embeddings-based Relational Schema Matching.". In EDBT/ICDT Workshops. 2020. PDF.

Alessandro Bozzon Ioannis Petros Samiotis, Sihang Qiu, Andrea Mauri, Cynthia CS Liem, Christoph Lofi. "Microtask crowdsourcing for music score Transcriptions: an experiment with error detection". In International Society for Music Information Retrieval Conference. 2020. PDF.

2019

Sepideh Mesbah, Jie Yang, Robert-Jan Sips, Manuel Valle Torre, Christoph Lofi, Alessandro Bozzon, and Geert-Jan Houben. "Training Data Augmentation for Detecting Adverse Drug Reactions in User-Generated Content". In Int. Conf. on Empirical Methods in Natural Language Processing (EMNLP). Hong Kong, China, nov 2019. PDF.

Daniel Vliegenhart, Sepideh Mesbah, Christoph Lofi, Akiko Aizawa, and Alessandro Bozzon. "Coner: A Collaborative Approach for Long-Tail Named Entity Recognition in Scienti c Publications". In Int. Conf. on Theory and Practice of Digital Libraries (TPDL). Oslo, Norway, sep 2019. PDF.

M.V. Torre, M. Ye, and C. Lofi. "Perceptual relational attributes: Navigating and discovering shared perspectives from user-generated reviews". In Lecture Notes in Informatics (LNI), Proceedings - Series of the Gesellschaft fur Informatik (GI), volume P-289. 2019. DOI.

Manuel Valle Torre, Mengmeng Ye, and Christoph Lofi. "Perceptual Relational Attributes: Navigating and Discovering Shared Perspectives from User-Generated Reviews". In Datenbanksysteme für Business, Technologie und Web (BTW). Rostock, Germany, 2019. PDF.

Laurens Van Den Bercken, Robert-Jan Sips, and Christoph Lofi. "Evaluating neural text simplification in the medical domain". In The Web Conference 2019 - Proceedings of the World Wide Web Conference, WWW 2019. 2019. PDF, DOI.

2018

Tarmo Robal, Yue Zhao, Christoph Lofi, and Claudia Hauff. "Towards Real-time Webcam-based Attention Tracking in Online Learning". In ACM Annual Meeting of Interactive User Interfaces (IUI). Tokyo, Japan, 2018. PDF.

Yue Zhao, Tarmo Robal, Christoph Lofi, and Claudia Hauff. "Towards MOOC2GO: The impact of mobile learning on learner performance in MOOCs". In Conf. on User Modeling, Adaptation and Personalization (UMAP). Singapore, 2018. PDF.

Sepideh Mesbah, Christoph Lofi, Manuel Valle Torre, Alessandro Bozzon, and Geert-Jan Houben. "TSE-NER: An Iterative Approach for Long-Tail Entity Extraction in Scientific Publications". In Int. Semantic Web Conference (ISWC). Monterey, California, USA, 2018. PDF.

Sepideh Mesbah, Alessandro Bozzon, Christoph Lofi, and Geert-Jan Houben. "SmartPub: A Platform for Long-Tail Entity Extraction from Scientific Publications". In The Web Conference (WWW) Demo Track. Lyon, France, 2018. PDF.

Tarmo Robal, Yue Zhao, Christoph Lofi, and Claudia Hauff. "IntelliEye: Enhancing MOOC Learners' Video Watching Experience with Real-Time Attention Tracking". In ACM Conf. on Hypertext and Social Media. Baltimore, Maryland, USA, 2018. PDF.

Sepideh Mesbah, Guanliang Chen, Manuel Valle Torre, Alessandro Bozzon, Christoph Lofi, and Geert-Jan Houben. "Concept Focus: Semantic Meta-Data For Describing MOOC Content". In Europ. Conf. on Technology Enhanced Learning (EC-TEL). Leeds, UK, 2018. PDF.

Yue Zhao, Tarmo Robal, Christoph Lofi, and Claudia Hauff. "Can I have a Mooc2Go, please? On The Viability of Mobile vs. Stationary Learning". In Europ. Conf. on Technology Enhanced Learning (EC-TEL). Leeds, UK, 2018. PDF.

2017

Jan-Christoph Kalo, Christoph Lofi, René Pascal Maseli, and Wolf-Tilo Balke. "Semantic Query Processing: Estimating Relational Purity". In Lernen Wissen Daten Analysen (LWDA) Conference. Rostock, Germany, sep 2017. PDF.

Yue Zhao, Christoph Lofi, and Claudia Hauff. "Scalable Mind-Wandering Detection for MOOCs: A Webcam-Based Approach". In European Conf. on Technology Enhanced Learning (EC-TEL). Tallinn, Estonia, sep 2017. PDF.

Mengmeng Ye, Christoph Lofi, and Nava Tintarev. "Memorability of Semantically Grouped Online Reviews". In Semantics 2017. Amsterdam, Netherlands, sep 2017. PDF.

Sepideh Mesbah, Kyriakos Fragkeskos, Christoph Lofi, Alessandro Bozzon, and Geert-Jan Houben. "Facet Embeddings for Explorative Analytics in Digital Libraries". In Int. Conf. on Theory and Practice of Digital Libraries (TPDL). Thessaloniki, Greece, sep 2017. PDF.

Christoph Lofi and Nava Tintarev. "Towards Analogy-based Recommendation: Benchmarking of Perceived Analogy Semantics". In Workshop on Recommendation in Complex Scenarios @ RecSys. Como, Italy, aug 2017. PDF.

Nava Tintarev and Christoph Lofi. "Sequences of Diverse Song Recommendations". In User Modelling, Adaptation and Personalization (UMAP). Bratislava, Slovakia, jul 2017. PDF.

Yue Zhao, Dan Davis, Guanliang Chen, Christoph Lofi, Claudia Hauff, and Geert-Jan Houben. "Certificate Achievement Unlocked: How Does MOOC Learners' Behaviour Change?". In User Modelling, Adaptation and Personalization (UMAP), 83–88. Bratislava, Slovakia, jul 2017. PDF.

Sepideh Mesbah, Kyriakos Fragkeskos, Christoph Lofi, Alessandro Bozzon, and Geert Jan Houben. "Semantic annotation of data processing pipelines in scientific publications". In European Semantic Web Conference (ESWC), volume 10249 LNCS, 321–336. Portoroz, Slovenia, may 2017. PDF, DOI.

Sepideh Mesbah, Alessandro Bozzon, Christoph Lofi, and Geert-Jan Houben. "Describing data processing pipelines in scientific publications for Big Data injection". In Workshop on Scholary Web Mining (SWM). Cambridge, UK, feb 2017. PDF, DOI.

Christoph Lofi and Manuel Valle Torre. "Perceptual Perspectives for Experience Items: Representation and Query Processing". In Dutch-Belgian DataBase Day (DBDBD). Utrecht, Netherlands, 2017. PDF.

2016

Christoph Lofi and Wolf-tilo Balke. "Large Scale Cooperation Scenarios – Crowdsourcing and its Societal Implication". Transactions on Internet Research (TIR), 12(1):03–14, jan 2016. PDF.

Christoph Lofi. "Towards Human-Centered Database Query Processing using on Perceptual Properties". In Dutch-Belgian DataBase Day (DBDBD). Mons, Belgium, 2016. PDF.

Christoph Lofi. "Measuring Semantic Similarity and Relatedness with Distributional and Knowledge-based Approaches". Database Society of Japan (DBSJ) Journal, 14(3):1–9, 2016. PDF, DOI.

Christoph Lofi, Athiq Ahamed, Pratima Kulkarni, and Ravi Thakkar. "Benchmarking semantic capabilities of analogy querying algorithms". In Int. Conf. on Database Systems for Advanced Applications (DASFAA), volume 9642, 463–478. Dallas, TX, USA, 2016. PDF, DOI.

2015

Nestor Alvaro, Mike Conway, Son Doan, Christoph Lofi, John Overington, and Nigel Collier. "Crowdsourcing Twitter annotations to identify first-hand experiences of prescription drug use". Journal of Biomedical Informatics, 58:280–287, nov 2015. PDF.

Christoph Lofi and Philipp Wille. "Exploiting social judgements in big data analytics". In 13th Lernen Wissen Adaption (LWA) Conference, volume 1458, 444–455. Trier, Germany, oct 2015. PDF.

Philipp Wille, Christoph Lofi, and Wolf-Tilo Balke. "Towards Narrative Information Systems". In Web-Age Information Management (WAIM). Qingdao, Shandong, China, jun 2015. PDF.

Kinda El Maarry. "Crowdsourcing for Query Processing on Web Data: A Case Study on the Skyline Operator". Journal of Computing and Information Technology (CIT), mar 2015. PDF.

Christoph Lofi and Christian Nieke. "I would like to watch something like ‘The Terminator'” Cooperative Query Personalization Based on Perceptual Similarity". In 18th International Conference on Extending Database Technology (EDBT). Brussels, Belgium, 2015. PDF.

2014

Jiyin He, Kai Kunze, Christoph Lofi, K. Madria Sanjay, and Stephan Sigg. "Towards Mobile Sensor-Aware Crowdsourcing: Architecture, Opportunities and Challenges". In DASFAA Workshop on Uncertain and Crowdsourced Data. Bali, Indonesia, 2014. PDF.

Christoph Lofi and Christian Nieke. "Exploiting Perceptual Similarity: Privacy-Preserving Cooperative Query Personalization". In Int. Conf. on Web Information System Engineering (WISE). Thessaloniki, Greece, 2014. PDF.

C. Lofi, C. Nieke, and N. Collier. "Discriminating Rhetorical Analogies in Social Media". In Conf. of the Europ. Chapter of the Association for Computational Linguistics (EACL). Gothenburg, Sweden, 2014. PDF.

Christoph Lofi and Kinda El Maarry. "Design Patterns for Hybrid Algorithmic-Crowdsourcing Workflows". In 16th IEEE Conf. on Business Informatics (CBI). Geneva, Switzerland, 2014. PDF.

2013

Christoph Lofi, Kinda El Maarry, and Wolf-Tilo Balke. "Skyline Queries over Incomplete Data - Error Models for Focused Crowd-Sourcing". In Int. Conf. on Conceptual Modeling (ER). Hong Kong, China, 2013. PDF.

Christoph Lofi, Kinda El Maarry, and Wolf-Tilo Balke. "Skyline Queries in Crowd-Enabled Databases". In Int. Conf. on Extending Database Technology (EDBT). Genoa, Italy, 2013. PDF.

Christoph Lofi and Christian Nieke. "Modeling Analogies for Human-Centered Information Systems". In 5th Int. Conf. On Social Informatics (SocInfo). Kyoto, Japan, 2013. PDF.

Christoph Lofi. "Just ask a human? – Controlling Quality in Relational Similarity and Analogy Processing using the Crowd". In CDIM Workshop at Database Systems for Business Technology and Web (BTW). Magdeburg, Germany, 2013. PDF.

Christoph Lofi. "Analogy Queries in Information Systems – A New Challenge". Journal of Information & Knowledge Management (JIKM), 2013. PDF.

2012

Christoph Lofi and Ralf Krestel. "iParticipate: Automatic Tweet Generation from Local Government Data". In 17th International Conference on Database Systems for Advanced Applications (DASFAA). Busan, South Korea, 2012. PDF.

Joachim Selke, Christoph Lofi, and Wolf-Tilo Balke. "Pushing the Boundaries of Crowd-Enabled Databases with Query-Driven Schema Expansion". Int. Conf. on Very Large Data Bases (VLDB), 5(2):538–549, 2012. PDF.

Christoph Lofi and Wolf-Tilo Balke. "On Skyline Queries and how to Choose from Pareto Sets". In Advanced Query Processing in Intelligent Systems Reference Library (ISRL 36), chapter 2, pages 15–36. Springer, 2012. PDF.

Christoph Lofi, Wolf-Tilo Balke, and Ulrich Güntzer. "Malleability-Aware Skyline Computation on Linked Open Data". In 17th International Conference on Database Systems for Advanced Applications (DASFAA). Busan, South Korea, 2012. PDF.

Christoph Lofi, Joachim Selke, and Wolf-Tilo Balke. "Information Extraction Meets Crowdsourcing: A Promising Couple". Datenbank-Spektrum, 2012. PDF, DOI.

Christoph Lofi, Wolf-tilo Balke, and Ulrich Güntzer. "Equivalence Heuristics for Malleability-Aware Skylines". Journal of Computing Science and Engineering (JCSE), 6(3):207–218, 2012. PDF.

2011

Silviu Homoceanu, Michael Loster, Christoph Lofi, and Wolf-tilo Balke. "Will I like it ? – Providing Product Overviews based on Opinion Excerpts". In IEEE Conference on Commerce and Enterprise Computing (CEC). Luxembourg, Luxembourg, 2011. PDF.

Christoph Lofi, Wolf-Tilo Balke, and Ulrich Güntzer. "Eliciting Customer Wishes using Example-Based Heuristics in E-Commerce Applications". In IEEE Conference on Commerce and Enterprise Computing (CEC). Luxembourg, Luxembourg, 2011. PDF.

Christoph Lofi. "Choosing the Right Thing: Cooperative Trade-Off Enhanced Skyline Queries". In PhD Workshop at the 28th International Conference On Data Engineering (ICDE). Hannover, Germany, 2011. PDF.

2010

Christoph Lofi and Wolf-Tilo Balke. "Preference Trade-Offs – Towards Manageable Skylines". In 22. GI-Workshop Grundlagen von Datenbanken (GvD). Bad Helmstedt, Germany, 2010. PDF.

Christoph Lofi, Christian Nieke, and Wolf-Tilo Balke. "Mobile Product Browsing Using Bayesian Retrieval". In IEEE Conf. Commerce and Enterprise Comp. (CEC). Shanghai, China, 2010. PDF.

Joachim Selke, Christoph Lofi, and Wolf-Tilo Balke. "Highly Scalable Multiprocessing Algorithms for Preference-Based Database Retrieval". In 15th International Conference on Database Systems for Advanced Applications (DASFAA). Tsukuba, Japan, 2010. PDF.

Christoph Lofi, Ulrich Güntzer, and Wolf-Tilo Balke. "Efficient Computation of Trade-Off Skylines". In 13th International Conference on Extending Database Technology (EDBT). Lausanne, Switzerland, 2010. PDF.

2009

Christoph Lofi, Wolf-Tilo Balke, and Ulrich Güntzer. "Efficient Skyline Refinement Using Trade-Offs". In 3rd International IEEE Conference on Research Challenges in Information Science (RCIS). Fès, Morocco, 2009. PDF, DOI.

Christoph Lofi, Wolf-Tilo Balke, and Ulrich Güntzer. "Efficient Skyline Refinement Using Trade-Offs Respecting Don't-Care Attributes". International Journal of Computer Science and Applications (IJCSA), 6(5):1–29, 2009. PDF.

2008

Christoph Lofi, W.-T. Wolf-Tilo Balke, Ulrich Güntzer, and U. Guntzer. "Efficiently Performing Consistency Checks for Multi-Dimensional Preference Trade-Offs". In 2nd International IEEE Conference on Research Challenges in Information Science (RCIS), volume 5, 271–278. Marakech, Morocco, 2008. IEEE. PDF, DOI.

Christoph Lofi, Wolf-Tilo Balke, and Ulrich Güntzer. "Consistency Check Algorithms for Multi-Dimensional Preference Trade-Offs". International Journal of Computer Science & Applications (IJCSA), 5(3):165–185, 2008. PDF.

2007

Wolf-Tilo Balke, Christoph Lofi, and Ulrich Güntzer. "User Interaction Support for Incremental Refinement of Preference-Based Queries". In 1st International IEEE Conference on Research Challenges in Information Science (RCIS). Ouarzazate, Morocco, 2007. PDF.

Christoph Lofi and Wolf Siberski. "Service Oriented Architectures for Open E-Learning Systems: An Overview of the Prolix Project". In eTeaching & eScience. Hannover, Germany, 2007. PDF.

Wolf-Tilo Balke, Christoph Lofi, and Ulrich Güntzer. "Incremental Trade-Off Management for Preference Based Queries". International Journal of Computer Science & Applications (IJCSA), 4(2):75–91, 2007. PDF.

Wolf-Tilo Balke, Ulrich Güntzer, and Christoph Lofi. "Eliciting Matters - Controlling Skyline Sizes by Incremental Integration of User Preferences". In 12th International Conference on Database Systems for Advanced Applications (DASFAA). Bangkok, Thailand, 2007. PDF.

Juri L. De Coi, Eelco Herder, Arne Koesling, Christoph Lofi, Daniel Olmedilla, Odysseas Papapetrou, and Wolf Siberski. "A Model for Competence Gap Analysis". In 3rd International Conference on Web Information Systems and Technologies (WEBIST). Barcelona, Spain, 2007. PDF, DOI.

2005

Christoph Lofi. "cGQM - Ein zielorientierter Ansatz für kontinuierliche, automatisierte Messzyklen". In 4th National Conference on Software Measurement and Metrics (DASMA MetriKon 2005). Kaiserslautern, Germany, 2005. PDF.

Data is widely accepted as one of the most valuable assets for many industrial and governmental organizations. At the heart of the data-driven economy lies the ability to provide value-adding services based on that data, which typically rely on purposefully analyzing and providing data to users and stakeholders.

Data needs to be fit for its intended purpose. Especially, the shape and properties of data must be fit for the chosen data analysis methods (e.g., machine-learning based techniques) and human-data interaction paradigms. However, the required information, if available at all, is often scattered across different heterogeneous sources, is incomplete or of bad quality, is lacking in semantic richness, or information is just implicitly available. Here, the role of Data Engineering research is to enable the development of data processing pipelines bridging the gap between available source data and the required target data.

My research focuses on Semantics-based Data Engineering methods and techniques, and especially on scenarios when the gap between source and target is rooted in a semantic structural mismatch. This is a dominant issue when dealing with data produced directly or indirectly by humans: most analysis and query techniques for tackling the requirements of such application domains demand explicitly structured high-quality data. However, human-produced data like natural text is typically unstructured and only implicitly mentions the desired information. The semantics of such unstructured data is often unclear or ambiguous and cannot easily be processed. Furthermore, human data is typically produced in a distributed fashion. Thus, the resulting challenge is to model what kind of target data is desired by the application domain, and then engineer data processing pipelines which integrate, transform, and augment the existing implicit and unstructured source data to comply with that model. My research focuses on the principled methods and insights to enable and support this engineering process.

As a simplified example, consider the following scenario: in sophisticated scientific document management system which recommends relevant research papers to users, information on research papers can be found in limited extent in structured bibliographic datasets, but mostly in the unstructured full-texts, on social media, or in talks or lectures. These highly heterogenous sources first need to be integrated, cleaned, and then transformed and augmented such that recommendation or query algorithms can use that data effectively, e.g. by extracting structured data from full texts or analyzing and summarizing the social media posts. Then, this data can be used for semantically rich exploration, recommendation, or visualization.

For realizing pipelines for integrating, transforming, and augmenting, I am employing a toolbox of different semantic enhancement methods. These covers:

  • Natural Language Processing methods, and especially language embeddings for analyzing natural text. I use these techniques to represent unstructured text fragments in latent spaces such that they can be analyzed, clustered, and classified using other data analytics techniques.
  • Information Extraction methods, and especially named entity recognition and named entity typing techniques for extracting keywords of specific types for summarizing or describing unstructured text content and linking them to semantic knowledge bases.
  • Crowd Computing to support all aspects of the developed data processing pipelines where fully automated methods fail. Crowd computing is used to train or verify other algorithms, but also for developing hybrid processing pipelines where users work together with automated methods. This is typically required as the semantic gap exhibited by many application domains is quite large, and automated techniques will typically need human guidance and cooperation.
  • AI-driven Data Analysis methods for drawing conclusions and reasoning during individual steps of the data processing pipeline.

 

Applications

The foundational challenge of researching and developing semantics-based data engineering methods must also be seen in the light of the intended application domains, as the notion of “data being fit to purpose” is domain dependent. I chose application domains which strongly exhibit the problem features relevant to my research focus: source data is typically highly unstructured and implicit in its semantics, and target data requires structure and explicit semantics.

The core applications I currently explore are digital libraries, online education information systems, and information systems for supporting digital humanities research.

  • In the digital library domain, I investigate data engineering workflows for augmenting existing metadata repositories with additional metadata types which allow for more meaningful exploration and visualization of large scientific document collections. To this end, natural language processing methods for extracting information from documents are combined with semantic modelling and crowd computing. In this domain, I cover both digital offerings of traditional libraries but also enterprise digital text repositories like medical information systems.
  • In the domain of information systems for digital humanities, I research data engineering workflows for integrating and transforming data from different sources of low quality (e.g. digital document scans) to higher quality formats (unified and annotated semantic digital documents). Due to the low quality and diversity of the raw data sources, resulting data engineering pipelines make heavy use of crowd-computing techniques.
  • In the online education domain, I focus on data engineering methods integrating and augmenting repositories with semantically more meaningful meta-data. This metadata is used to also develop richer exploration and interaction paradigms.

 

 

Dr. C. Lofi

Visiting Address
Building 28

Room: 4.E.100 East 4rd floor
Van Mourik Broekmanweg 6
2628 XE Delft
The Netherlands

Mailing Address
EEMCS, Web Information Systems
P.O. Box 5031, 2600 GA Delft
The Netherlands