Since September 2006, I am a professor at the Faculty of Computer Science of the Technische Universität Dortmund where I am heading the Foundations of Computer Science and Computer Science Education Group at the Chair of Algorithm Engineering. I recieved my PhD from the Department of Computer Science of the University of Münster in 1999; my dissertation topic was “External Memory Algorithms for Geographic Information Systems”. In 2004, I have been given the venia legendi in Computer Science; the Habilitation topic was “Large-Scale Algorithms and Data Structures for Dynamic and Time-Variant Geometric Problems”.

My current research and teaching interests lie in the following areas:

• Algorithms and Data Structures, in particular for geometry-related problems
• Algorithm Engineering, in particular I/O- and cache-efficiency
• Computer Science Education, in particular (mis)conceptions and lower secondary education

As a participant in the ”Templated Portable I/O-Environment” project (see also the TPIE-page on ohloh.net) I am involved in the evaluation and further development of the TPIE software library.

In the past, I have held (temporary) positions at the following institutions:

• University of Münster (Münster, Germany).
• University for Health Informatics and Technology Tyrol (Innsbruck, Austria).
• University of Siegen (Siegen, Germany).

• Collaborative Research Center (Sonderforschungsbereich) 876, Project A2 "Algorithmic aspects of learning methods in embedded systems" (together with C. Sohler).
• dortMINT - Diagnose und individuelle Förderung in der MINT-Lehrerbildung, Projekt I2 "Diagnose und individuelle Förderung erlernen in der fachdidaktischen Ausbildung" (mit D. Graf [Biologie], I. Melle [Chemie], M. Nührenbörger [Mathematik] und F. Wember [Rehabilitationswissenschaften]).

• EuroCG 2010 (PC Chair), ISSEP 2010 (PC Co-Chair), SEA 2009 (PC Chair), ESA 2007 [Engineering and Applications Track], WEA 2007, Massive 2005 (Co-Chair), ALENEX 2004.

• Jan Vahrenhold. B-trees. In: Ming-Yang Kao, editor, Encyclopedia of Algorithms, pages 108–112. Springer, Berlin, 2008.
• Christian Breimann and Jan Vahrenhold. External Memory Computational Geometry Revisited. Chapter 6 in: Ulrich Meyer, Peter Sanders, and Jop Sibeyn, editors, Algorithms for Memory Hierarchies, volume 2625 of Lecture Notes in Computer Science, pages 110–148. Springer, Berlin, 2003. © Springer-Verlag. (The full bibliography of the volume can be accessed here.)

• Fabian Gieseke, Gabriel Moruz, and Jan Vahrenhold. Resilient K-d Trees: K-Means in Space Revisited. Frontiers of Computer Science (ICDM 2010 Special Issue), Online First (accepted November 2011).
• Fabian Gieseke, Joachim Gudmundsson, and Jan Vahrenhold. Pruning Spanners and Constructing Well-Separated Pair Decompositions in the Presence of Memory Hierarchies. Journal of Discrete Algorithms 8(3):259–272, September 2010.
• Henrik Blunck and Jan Vahrenhold. In-Place Algorithms for Computing (Layers of) Maxima. Algorithmica 57(1):1–21, May 2010.
• Nicola Beume, Carlos M. Fonseca, Manuel López-Ibáñez, Luís Paquete, and Jan Vahrenhold. On the Complexity of Computing the Hypervolume Indicator. IEEE Transactions on Evolutionary Computation 13(5):1075–1082. October 2009.
• Thomas Hazel, Laura Toma, Jan Vahrenhold, and Rajiv Wickremesinghe. TerraCost: A Versatile and Scalable Approach to Computing Least-Cost-Path Surfaces for Massive Grid-Based Terrains. ACM Journal of Experimental Algorithmics. Volume 12, Article 1.9, June 2008.
• Jan Vahrenhold. Line-Segment Intersection Made In-Place. Computational Geometry: Theory and Applications 38(3):213–230, October 2007.
• Prosenjit Bose, Anil Maheshwari, Pat Morin, Jason Morrison, Michiel Smid, and Jan Vahrenhold. Space-Efficient Geometric Divide-and-Conquer Algorithms. Computational Geometry: Theory and Applications 37(3):209–227, August 2007.
• Jan Vahrenhold. An In-Place Algorithm for Klee's Measure Problem in Two Dimensions. Information Processing Letters 102(4):169–174, May 2007.
• Lars Arge and Jan Vahrenhold. I/O-Efficient Dynamic Planar Point-Location. Computational Geometry: Theory and Applications 29(2):147–162, October 2004.
• Pankaj K. Agarwal, Mark de Berg, Sariel Har-Peled, Mark H. Overmars, Micha Sharir, and Jan Vahrenhold. Reporting Intersecting Pairs of Polytopes in Two and Three Dimensions. Computational Geometry: Theory and Applications 23(2):195–207, September 2002.
• Jan Vahrenhold and Klaus H. Hinrichs. Planar Point Location for Large Data Sets: To Seek or Not To Seek. ACM Journal of Experimental Algorithmics. Volume 7, Article 8, August 2002.
• Lars Arge, Klaus H. Hinrichs, Jan Vahrenhold, and Jeffrey S. Vitter. Efficient Bulk Operations on Dynamic R-trees. Algorithmica 33(1):104–128, March 2002.
• Rüdiger Köhling, Jens Reinel, Jan Vahrenhold, Klaus H. Hinrichs, and Erwin-Josef Speckmann. Spatio-Temporal Patterns of Neuronal Activity: Analysis of Optical Imaging Data Using Geometric Shape Matching. Journal of Neuroscience Methods 114(1):17–23, February 2002.

• Holger Danielsiek, Wolfgang Paul, and Jan Vahrenhold: Detecting and Understanding Students' Misconceptions Related to Algorithms and Data Structures, In: Tracy Camp and Paul Tymann, editors: Proceedings of the 43rd ACM Technical Symposium on Computer Science Education (SIGCSE 2012), pages 21-26, ACM Press, 2012. © Copyright 2012 by ACM, Inc.
• Arno Pasternak and Jan Vahrenhold: Design and Evaluation of a Braided Teaching Course in Sixth Grade Computer Science Education, In: Tracy Camp and Paul Tymann, editors: Proceedings of the 43rd ACM Technical Symposium on Computer Science Education (SIGCSE 2012), pages 45-50, ACM Press, 2012. © Copyright 2012 by ACM, Inc.
• Renate Thies and Jan Vahrenhold: Reflections on Outreach Programs in CS Classes: Learning Objectives for "Unplugged" Activities, In: Tracy Camp and Paul Tymann, editors: Proceedings of the 43rd ACM Technical Symposium on Computer Science Education (SIGCSE 2012), pages 487-492, ACM Press, 2012. © Copyright 2012 by ACM, Inc.
• Jan Vahrenhold: On Misconceptions and Implementing 'A Class Defines a Data Type', In: Daniela Bezáková and Ivan Kalaš, editors: Proceedings of Selected Papers of the 5th International Conference on Informatics in Schools: Situation, Evolution and Perspectives (ISSEP 2011), 12 pages.
• Christian Scheffer and Jan Vahrenhold: Approximating Geodesic Distances on 2-Manifolds in R³, In: Greg Aloupis and David Bremner, editors: Proceedings of the 23rd Canadian Conference on Computational Geometry (CCCG 2011), pages 325–330. Toronto, 2011.
• Fabian Gieseke, Gabriel Moruz, and Jan Vahrenhold: Resilient K-d Trees: K-Means in Space Revisited, In: Proceedings of the 10th IEEE International Conference on Data Mining (ICDM 2010), pages 815–820. IEEE Computer Society, 2010. © Copyright 2010, IEEE.
• Fabian Gieseke, Kai Lars Polsterer, Andreas Thom, Peter Zinn, Dominik Bomans, Ralf-Jürgen Dettmar, Oliver Kramer, and Jan Vahrenhold: Detecting Quasars in Large-Scale Astronomical Surveys, In: Proceedings of the Ninth International Conference on Machine Learning and Applications (ICMLA 2010), pages 352–357. IEEE Press, 2010. © Copyright 2010, IEEE.
• Arno Pasternak and Jan Vahrenhold: Braided Teaching in Secondary CS Education: Contexts, Continuity, and the Role of Programming, In: Tom Cortina and Ellen Walker, editors: Proceedings of the 41st ACM Technical Symposium on Computer Science Education (SIGCSE 2010), pages 204–208, ACM Press, 2010. © Copyright 2010 by ACM, Inc.
• Arno Pasternak and Jan Vahrenhold: Rote Fäden und Kontextorientierung im Informatikunterricht, In: Ingo-Rüdiger Peters, editor: Informatische Bildung in Theorie und Praxis, 13. GI-Fachtagung - Informatik und Schule (INFOS 2009), pages 45–56. Berlin, 2009. LOG IN Verlag. In German.
• Ludger Becker, Hannes Partzsch, and Jan Vahrenhold: Query Responsive Index Structures, In: Proceedings of the Fifth International Conference on Geographic Information Science (GIScience 2008), volume 5266 of Lecture Notes in Computer Science, pages 1–19. Springer, Berlin, 2008. © Springer-Verlag.
• Frank Steinicke, Christian Jansen, Klaus Hinrichs, Jan Vahrenhold, and Bernd Schwald: Generating Optimized Marker-Based Rigid Bodies for Optical Tracking Systems, In: A. Ranchordas, H. Araújo, and J. Vitrià, editors: Proceedings of the Second International Conference on Computer Vision Theory and Applications (VISAPP 2007), pages 387–395, INSTICC Press, Barcelona, 2007.
• Jennis Meyer-Spradow, Timo Ropinski, Jan Vahrenhold, Klaus Hinrichs: Illustrating Dynamics of Time-Varying Volume Datasets in Static Images, In: Leif Kobbelt, Torsten Kuhlen, Til Aach, and Rüdiger Westermann, editors: Proceedings of the 11th International Fall Workshop on Vision, Modeling, and Visualization (VMV 2006), pages 333–340. Akademische Verlagsgesellschaft AKA, Berlin, 2006.
• Henrik Blunck, Klaus H. Hinrichs, Joëlle Sondern, and Jan Vahrenhold. Modeling and Engineering Algorithms for Mobile Data. In: Andreas Riedl, Wolfgang Kainz, and Gregory A. Elmes, editors: Progress in Spatial Data Handling: Proceedings of the 12th International Symposium on Spatial Data Handling (SDH 2006), pages 61–77. Springer, Berlin, 2006. © Springer-Verlag.
• Henrik Blunck and Jan Vahrenhold. In-Place Algorithms for Computing (Layers of) Maxima. In: Lars Arge and Rusin Freivalds, editors: Proceedings of the 10th Scandinavian Workshop on Algorithm Theory (SWAT 2006), volume 4059 of Lecture Notes in Computer Science, pages 363–374. Springer, Berlin, 2006. © Springer-Verlag.
• Henrik Blunck and Jan Vahrenhold. In-Place Randomized Slope Selection. In: Tiziana Calamoneri, Irene Finocchi, and Giuseppe F. Italiano, editors: Proceedings of the 6th Conference on Algorithms and Complexity (CIAC 2006), volume 3998 of Lecture Notes in Computer Science, pages 30–41. Springer, Berlin, 2006. © Springer-Verlag.
• Thomas Hazel, Laura Toma, Jan Vahrenhold, and Rajiv Wickremesinghe. TerraCost: A Versatile and Scalable Approach to Computing Least-Cost-Path Surfaces for Massive Grid-Based Terrains (Extended Abstract). In: Proceedings of the 21th Annual ACM Symposium on Applied Computing (SAC '06), pages 52–57, ACM Press, 2006. © Copyright 2006 by ACM, Inc.
• Joachim Gudmundsson and Jan Vahrenhold. I/O-Efficiently Pruning Dense Spanners. In: Jin Akiyama, Mikio Kano, and Xuehou Tan, editors: Revised Selected Papers of the Japanese Conference on Discrete and Computational Geometry (JCDCG 2004), volume 3742 of Lecture Notes in Computer Science, pages 106–116. Springer, Berlin, 2005. © Springer-Verlag.
• Jan Vahrenhold. Line-Segment Intersection Made In-Place. In: Alejandro López-Ortiz, Frank Dehne, and Jörg-Rüdiger Sack, editors: Proceedings of the Ninth International Workshop on Algorithms and Data Structures (WADS 2005), volume 3608 of Lecture Notes in Computer Science, pages 146–157. Springer, Berlin, 2005. © Springer-Verlag.
• Henrik Blunck, Klaus H. Hinrichs, Iris Puke, and Jan Vahrenhold. Verarbeitung von Trajektorien mobiler Objekte. In: Martin Raubal, Adam Sliwinski, and Werner Kuhn, editors: Geoinformation und Mobilität - von der Forschung zur praktischen Anwendung. Beiträge zu den Münsteraner GI-Tagen 2004, volume 22 of IfGI prints, pages 29–41, 2004. In German.
• Ludger Becker, Henrik Blunck, Klaus H. Hinrichs, and Jan Vahrenhold. A Framework for Representing Moving Objects. In: F. Galino, M. Takizawa, and R. Traunmüller: Proceedings of the 15th International Conference on Database and Expert Systems Applications, volume 3180 of Lecture Notes in Computer Science, pages 854–863. Springer, Berlin, 2004. © Springer-Verlag.
• Ludger Becker, Tobias Gerke, Klaus H. Hinrichs, Tina Strauf née Hausmann, and Jan Vahrenhold. An XML- and Log-Based Infrastructure For Evaluating And Teaching Spatio-Temporal Indexing Schemes. In: Proceedings of the First International Workshop on Geographic Information Management (in: Proceedings of the Fifteenth International Workshop on Database and Expert Systems Applications), pages 851–855, IEEE Computer Society Press, 2004. © IEEE.
• Anil Maheshwari, Jan Vahrenhold, and Norbert Zeh. On Reverse Nearest Neighbor Queries (Extended Abstract). In: Steven Wismath, editor, Proceedings of the 14th Canadian Conference on Computational Geometry, pages 128–132. Lethbridge, 2002.
• Pankaj K. Agarwal, Lars Arge, and Jan Vahrenhold. Time Responsive External Data Structures for Moving Points. In: Frank Dehne, Jörg-Rüdiger Sack, and Roberto Tamassia, editors, Proceedings of the Seventh International Workshop on Algorithms and Data Structures (WADS 2001), volume 2125 of Lecture Notes in Computer Science, pages 50–61. Springer, Berlin, 2001. © Springer-Verlag.
• Pankaj K. Agarwal, Mark de Berg, Sariel Har-Peled, Mark H. Overmars, Micha Sharir, and Jan Vahrenhold. Reporting Intersecting Pairs of Polytopes in Two and Three Dimensions. In: Frank Dehne, Jörg-Rüdiger Sack, and Roberto Tamassia, editors, Proceedings of the Seventh International Workshop on Algorithms and Data Structures (WADS 2001), volume 2125 of Lecture Notes in Computer Science, pages 122–134. Springer, Berlin, 2001. © Springer-Verlag.
• Jan Vahrenhold and Klaus H. Hinrichs. Planar Point Location for Large Data Sets: To Seek or Not To Seek. In: Stefan Näher and Dorothea Wagner, editors, Proceedings of the Fourth Workshop on Algorithm Engineering (WAE 2000), volume 1982 of Lecture Notes in Computer Science, pages 183–194. Springer, Berlin, 2001. © Springer-Verlag.
• Lars Arge and Jan Vahrenhold. I/O-Efficient Dynamic Planar Point-Location (Extended Abstract). In: Proceedings of the 16th Annual ACM Symposium on Computational Geometry (SCG '00), pages 191–200. ACM Press, 2000. © Copyright 2000 by ACM, Inc.
• Lars Arge, Octavian Procopiuc, Sridhar Ramaswamy, Torsten Suel, Jan Vahrenhold, and Jeffrey S. Vitter. A Unified Approach for Indexed and Non-Indexed Spatial Joins. In: Carlo Zaniolo, Peter C. Lockemann, Marc H. Scholl, and Torsten Grust, editors, Advances in Database Technology - Proceedings of the 7th International Conference on Extending Database Technology (EDBT '00), volume 1777 of Lecture Notes in Computer Science, pages 413–429. Springer, Berlin, 2000. © Springer-Verlag.
• Ludger Becker, André Giesen, Klaus H. Hinrichs, and Jan Vahrenhold. Algorithms for Performing Map Overlay and Spatial Join for Massive Data Sets. In: Ralf Hartmut Güting, Dimitris Papadias, and Fred Lochovsky, editors, Advances in Spatial Databases - Proceedings of the Sixth International Symposium on Spatial Databases (SSD '99), volume 1651 of Lecture Notes in Computer Science, pages 270–285. Springer, Berlin, 1999. © Springer-Verlag.
• Lars Arge, Klaus H. Hinrichs, Jan Vahrenhold, and Jeffrey S. Vitter. Efficient Bulk Operations on Dynamic R-trees (Extended Abstract). In: Catherine C. McGeoch and Michael T. Goodrich, editors, Proceedings of the First Workshop on Algorithm Engineering and Experimentation (ALENEX '99), volume 1619 of Lecture Notes in Computer Science, pages 328–347. Springer, Berlin, 1999. © Springer-Verlag.

• Tim Bell, Arno Pasternak, Chris Stephenson, Allen B. Tucker, and Jan Vahrenhold. Implementing CS Curricula in Secondary Education: An International Perspective. In: Proceedings of the 40th Annual Frontiers in Education Conference (FIE 2010), pages T2B-1–T2B-3 , IEEE Computer Society, 2010, © Copyright 2010, IEEE.
• Chis Stephenson, Judith Gal-Ezer, Margot Philipps, and Jan Vahrenhold. Professional Associations in K-12 Computer Science. In: Proceedings of the 15th Annual Conference on Innovation and Technology in Computer Science Education (ITiCSE 2010), pages 329–330, ACM Press, 2010. © Copyright 2010 by ACM, Inc.

• Jan Vahrenhold (Ed.). Preface. Special issue of the ACM Journal of Experimental Algorithmics devoted to selected papers from the 8th Symposium on Experimental Algorithms. Volume 16, Section 2. May 2011.
• Jan Vahrenhold (Ed.). 26th European Workshop on Computational Geometry (EuroCG 2010), Proceedings. Dortmund, 2010.
• Juraj Hromkovič, Richard Královič, and Jan Vahrenhold (Eds.). Teaching Fundamentals Concepts of Informatics. 4th International Conference on Informatics in Secondary Schools - Evolution and Perspectives, ISSEP 2010, Zurich, Switzerland, January 13-15, 2010. Proceedings. Volume 5941 of Lecture Notes in Computer Science. Springer, Berlin, 2010.
• Jan Vahrenhold (Ed.). Experimental Algorithms. 8th International Symposium, SEA 2009. Dortmund, Germany, June 2009. Proceedings. Volume 5526 of Lecture Notes in Computer Science. Springer, Berlin, 2009.
• Lars Arge, Mark de Berg, and Jan Vahrenhold (Eds.). Workshop on Massive Geometric Data Sets (Massive2005), Proceedings. Technical Report 02/05 - I, Fachbereich 10, Universität Münster, 2005.

• Sylvie Temme and Jan Vahrenhold. Revisiting the Construction of SSPDs in the Presence of Memory Hierarchies. In: Walter Didimo and Giuseppe Liotta, editors: Proceedings of the 28th European Workshop on Computational Geometry (pdf), pages 57–60, 2012.
• Christian Scheffer and Jan Vahrenhold. Simplified Medial-Axis Approximation with Guarantees. In: Walter Didimo and Giuseppe Liotta, editors: Proceedings of the 28th European Workshop on Computational Geometry (pdf), pages 161–164, 2012.
• Christian Scheffer and Jan Vahrenhold. Learning a 2-Manifold with a Boundary in R³ (abstract). In: Michael Hoffmann, editor: Proceedings of the 27th European Workshop on Computational Geometry, pages 213–216, 2011.
• Fabian Gieseke and Jan Vahrenhold. Cache-Oblivious Construction of a Well-Separated Pair Decomposition. In: Stefan Langerman, editor: Proceedings of the 25th European Workshop on Computational Geometry, pages 341–344, 2009.
• Christian Jansen, Frank Steinicke, Klaus Hinrichs, Jan Vahrenhold, and Bernd Schwald: Performance Improvement for Optical Tracking by Adapting Marker Arrangements, In: G. Zachmann, editor: Proceedings of the VR Workshop on Trends and Issues in Tracking for Virtual Environments, pages 28–33, Shaker-Verlag, 2007.
• Henrik Blunck and Jan Vahrenhold. In-Place Randomized Slope Selection. In: Ioannis Emiris, Menelaos Karavelas, and Leonidas Palios, editors: Proceedings of the 22nd European Workshop on Computational Geometry, pages 177–180, 2006.
• Henrik Blunck and Jan Vahrenhold. In-Place Algorithms for Computing (Layers of) Maxima. In: Ioannis Emiris, Menelaos Karavelas, and Leonidas Palios, editors: Proceedings of the 22nd European Workshop on Computational Geometry, pages 181–184, 2006.
• Joachim Gudmundsson and Jan Vahrenhold. I/O-Efficiently Pruning Dense Spanners. In: Jin Akiyama and Mikio Kano, editors: Extended Abstracts of the Japan Conference on Discrete and Computational Geometry, pages 35–35, Japan, 2004.
• Prosenjit Bose, Anil Maheshwari, Pat Morin, Jason Morrison, Michiel Smid, and Jan Vahrenhold. Space-Efficient Geometric Divide-and-Conquer Algorithms. In: J. M. Díaz-Báñez, A. Márquez, and J. R. Portillo, editors: Proceedings of the 20th European Workshop on Computational Geometry, pages 65–68, 2004.
• Ludger Becker, Henrik Blunck, Klaus H. Hinrichs, and Jan Vahrenhold. Ein Rahmenwerk zur Repräsentation von sich bewegenden Objekten. In: Hagen Höpfner and Gunther Saake: Grundlagen und Anwendungen mobiler Informationstechnologie, pages 3–12, 2004. In German.

• Jan Vahrenhold. Large-Scale Algorithms and Data Structures for Dynamic and Time-Variant Geometric Problems. Habilitation Thesis. Münster, 2003.
• Jan Vahrenhold. External Memory Algorithms for Geographic Information Systems. PhD Thesis. Münster, 1999.
• Jan Vahrenhold. Triangulierung eines einfachen Polygons in linearer Zeit. Diploma Thesis (in German). Münster, 1996.

• TPIE: A Templated Portable I/O Environment (formerly known as: TPIE: A Transparent Parallel I/O-Environment), ongoing.
• TerraFlowExtension: I/O-efficient Flow Computation for Raster Data as an Extension for ArcGIS® 8.x.
• ImageViewer: Analysis of Optical Imaging Data Using Geometric Shape Matching (2000-2001).

Pankaj K. Agarwal, Lars Arge, Ludger Becker, Tim Bell, Mark de Berg, Nicola Beume, Henrik Blunck, Dominik Bomanns, Prosenjit Bose, Christian Breimann, Holger Danielsiek, Ralf-Jürgen Dettmar, Carlos M. Fonseca, Judith Gal-Ezer, Tobias Gerke, Fabian Gieseke, André Giesen, Joachim Gudmundsson, Sariel Har-Peled, Thomas Hazel, Juraj Hromkovič, Klaus H. Hinrichs, Christian Jansen, Rüdiger Köhling, Richard Královič, Oliver Kramer, Manuel López-Ibáñez, Anil Maheshwari, Jennis Meyer-Spradow, Pat Morin, Jason Morrison, Gabriel Moruz, Mark H. Overmars, Luís Paquete, Hannes Partzsch, Arno Pasternak, Wolfgang Paul, Margot Philipps, Kai Lars Polsterer, Octavian Procopiuc, Iris Puke, Sridhar Ramaswamy, Jens Reinel, Timo Ropinski, Christian Scheffer, Bernd Schwald, Micha Sharir, Michiel Smid, Joëlle Sondern, Torsten Suel, Erwin-Josef Speckmann, Frank Steinicke, Chris Stephenson, Tina Strauf, Sylvie Temme, Renate Thies, Andreas Thom, Laura Toma, Allen B. Tucker, Jeffrey S. Vitter, Rajiv Wickremesinghe, Norbert Zeh, Peter Zinn.