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Curriculum Vitae of Sylvain PION


My research is focused around the development of methods to achieve practical scalability of fundamental geometric algorithms. It spans the following domains : Exact Geometric Computation (arithmetic issues such as control of floating-point round-off errors, and exact arithmetic), generic programming and C++, compiler optimizations, efficiency of implementations, parallel algorithms (multi-core).  All this work was initially motivated by and applied in CGAL, the Computational Geometry Algorithms Library (http://www.cgal.org/), a large C++ Open Source and commercial project.

 

POSITIONS HELD

• Dec. 2017-present : Research scientist at INRIA Bordeaux, France.

• Apr. 2013-Jan. 2017 : Senior Software Engineer at Apple in Cupertino, CA, USA.

• Jan. 2011-Mar. 2013 : Software Engineer at Google in Mountain View, CA, USA.

• Oct. 2003-Dec. 2010 : Research scientist at INRIA Sophia Antipolis, France.

• Oct. 2002-Sep. 2003 : Post-doc at the Max Planck Institut für Informatik, Saarbrücken, Germany.

• Apr. 2002-Sep. 2002 : Post-doc at New York University, USA.

• Oct. 2000-Mar. 2002 : Post-doc at INRIA Sophia Antipolis, France.

• Dec. 1999-Sep. 2000 : Military service as scientific programmer.

 

EDUCATION

• 1996-1999 : Ph.D. at INRIA Sophia Antipolis directed by J.-D. Boissonnat : From computational geometry to geometric computing.  Diploma delivered by the University of Nice-Sophia Antipolis.

• 1995-1996 : Master (DEA/Magistère) at University Paris 7, in Computer Science (majors in computational geometry and cryptology).

• 1994-1998 : École Normale Supérieure de Paris.

 

PROFESSIONNAL EXPERIENCE

• Since Mar. 2020 : At INRIA Bordeaux, I am a standalone researcher, working on issues connected to certified arithmetics and compilers/languages.

• Dec. 2017-Feb. 2020 : At INRIA Bordeaux, I joined the new team Auctus with a research focus on collaborative robots, that is the cognitive and physical interaction of robots with humans.

• Apr. 2013-Jan 2017 : At Apple, I worked on various processing stages of maps vector data, mainly the buildings footprints data (mostly polygons with height information, sometimes more refined geometry or other attributes).  I was partly responsible for importing data from a few providers, as well as inferring attributes from other sources like GPS/iPhone probe data.  Most importantly, I designed and implemented geometric processing algorithms to fix overlapping issues with the road network, in a semi-automatic way.  I focused on 2 algorithms, the first fixed mis-alignment issues between several data sets coming from different providers (overall shifts).  The second one was more in line with geometry processing and improved over the first. This involved leveraging mostly several C++ libraries like CGAL, but also some Java/Scala programming, in the context of parallel processing using Hadoop.  Since January 2014, I shared the technical responsibility for the team handling the processing pipeline of building footprints data : a system allowing manual data editing as well as a number of automatic processing phases, and I helped transitioning our system to a new, more general, platform.

• Jan. 2011-Mar. 2013 : At Google, I worked in the Maps Ground Truth project which goal was to assemble Google’s own base map vector data, country by country.  I implemented maps data processing, mostly in Java, in a parallel setting.  A lot of data fixing was done, on the geometry aspect as well as other attributes like names.  I was responsible for “importing” data for 5 countries, which have been successfully launched (meaning that the data is now live on maps.google.com).

• 1997-2010 : At INRIA and during my post-docs at NYU and MPI, I did research in the field of Computational Geometry, focusing on robust and scalable implementations of geometric algorithms in the realm of Delaunay triangulations and mesh generation. Most of my work was in connection to the CGAL library (www.cgal.org) : I developed, optimized and maintained several key packages for triangulations and mesh generation, as well as the kernel of basic geometric routines, especially the numerical robustness and efficiency aspects.  I also worked on parallel algorithms, mostly a concurrent Delaunay triangulation for multi-core.  I took project-wide responsibilities within the CGAL Editorial Board (responsible for reviews and all technical decisions).  CGAL is now a mature project supported mostly commercially and an international success.

See e.g. : http://doc.cgal.org/latest/Triangulation_3/  (source code is available)

• 2005-2010 : C++ standardization within the ISO WG21 committee.  I co-authored several proposals around interval arithmeticdirected rounding arithmetic operations and multi-valued logic.  I also co-authored the Boost.Interval library.

 

TEACHING EXPERIENCE :

• 2007-2009 : Member of the selection board of the entrance examination of the Écoles Normales Supérieures.

• 2006-2007 : Master level courses at the Université de Bourgogne in Dijon, France.

 

ONLINE VIDEOS :

CGAL - The Open Source Computational Geometry Algorithms Library, Google Tech Talk, March 2008

La Bibliothèque CGAL, Séminaire au Collège de France, Avril 2017

The Arithmetic Toolbox in CGAL, Mini-Workshop on iRRAM/MPFR-MPC, Dagstuhl, Germany, April 19, 2018

 

PARTICIPATION IN COMMITTEES :

• 2006-2010 : Chair of the Editorial Board of the CGAL project.

• Conference program committees : SoCG 2006, ESA 2010, SoCG Multimedia/Video 2009.

  (SoCG is the Symposium on Computational Geometry, the main conference of the domain)

  (ESA is the European Symposium on Algorithms)

• Standardization committees : C++ (ISO/JTC1/SC22/WG21), interval arithmetic (IEEE 1788).

 

HOBBIES : Cycling, flying (paragliding, autogyros), piano, chess

 


Journal articles13 documents

  • Sylvain Pion, Andreas Fabri. A Generic Lazy Evaluation Scheme for Exact Geometric Computations. Science of Computer Programming, Elsevier, 2011, Special issue on library-centric software design (LCSD 2006), 76 (4), pp.307-323. ⟨10.1016/j.scico.2010.09.003⟩. ⟨inria-00562300⟩
  • Vicente Batista, David Millman, Sylvain Pion, Johannes Singler. Parallel Geometric Algorithms for Multi-Core Computers. Computational Geometry, Elsevier, 2010, Special Issue on the 25th Annual Symposium on Computational Geometry (SoCG'09), 43 (8), pp.663-677. ⟨10.1016/j.comgeo.2010.04.008⟩. ⟨inria-00488961⟩
  • Lutz Kettner, Kurt Mehlhorn, Sylvain Pion, Stefan Schirra, Chee Yap. Classroom examples of robustness problems in geometric computations. Computational Geometry, Elsevier, 2008, 40 (1), pp.61-78. ⟨10.1016/j.comgeo.2007.06.003⟩. ⟨inria-00344310⟩
  • Guillaume Melquiond, Sylvain Pion. Formally Certified Floating-Point Filters For Homogeneous Geometric Predicates. RAIRO - Theoretical Informatics and Applications (RAIRO: ITA), EDP Sciences, 2007, 41, pp.57-69. ⟨10.1051/ita:2007005⟩. ⟨inria-00071232v2⟩
  • Susan Hert, Michael Hoffmann, Lutz Kettner, Sylvain Pion, Michael Seel. An Adaptable and Extensible Geometry Kernel. Computational Geometry, Elsevier, 2007, Special Issue on CGAL, 38 (1-2), pp.16-36. ⟨10.1016/j.comgeo.2006.11.004⟩. ⟨inria-00344363⟩
  • Sylvain Pion. Des arithmétiques pour la géométrie. Interstices, INRIA, 2006. ⟨inria-00096418⟩
  • Hervé Brönnimann, Guillaume Melquiond, Sylvain Pion. The design of the Boost interval arithmetic library. Theoretical Computer Science, Elsevier, 2006, Real Numbers and Computers, 351 (1), pp.111-118. ⟨10.1016/j.tcs.2005.09.062⟩. ⟨inria-00344412⟩
  • Sylvain Pion, Chee Yap. Constructive root bound for k-ary rational input numbers. Theoretical Computer Science, Elsevier, 2006, 369 (1-3), pp.361-376. ⟨10.1016/j.tcs.2006.09.010⟩. ⟨inria-00344349⟩
  • Chen Li, Sylvain Pion, Chee Yap. Recent progress in exact geometric computation. Journal of Logic and Algebraic Programming, Elsevier, 2005, Practical development of exact real number computation, 64 (1), pp.85-111. ⟨10.1016/j.jlap.2004.07.006⟩. ⟨inria-00344355⟩
  • Olivier Devillers, Sylvain Pion, Monique Teillaud. Walking in a Triangulation. International Journal of Foundations of Computer Science, World Scientific Publishing, 2002, 13, pp.181--199. ⟨10.1142/S0129054102001047⟩. ⟨inria-00102194⟩
  • Jean-Daniel Boissonnat, Olivier Devillers, Sylvain Pion, Monique Teillaud, Mariette Yvinec. Triangulations in CGAL. Computational Geometry, Elsevier, 2002, 22, pp.5-19. ⟨10.1016/S0925-7721(01)00054-2⟩. ⟨inria-00167199⟩
  • Hervé Brönnimann, Christoph Burnikel, Sylvain Pion. Interval Arithmetic Yields Efficient Dynamic Filters for Computational Geometry. Discrete Applied Mathematics, Elsevier, 2001, pp.25-47. ⟨inria-00344281⟩
  • Hervé Brönnimann, Ioannis Emiris, Victor Y. Pan, Sylvain Pion. Sign Determination in Residue Number Systems. Theoretical Computer Science, Elsevier, 1999, Special issue on Real Numbers and Computers, 210, pp.173-197. ⟨inria-00344324⟩

Conference papers19 documents

  • Jihun Yu, Chee Yap, Zilin Du, Sylvain Pion, Hervé Brönnimann. The Design of Core 2: A Library for Exact Numeric Computation in Geometry and Algebra. Third International Congress on Mathematical Software, Sep 2010, Kobe, Japan. ⟨inria-00519591⟩
  • Vicente Batista, David Millman, Sylvain Pion, Johannes Singler. Parallel Geometric Algorithms for Multi-Core Computers. ACM Symposium on Computational Geometry, Jun 2009, Aarhus, Denmark. pp.217-226. ⟨inria-00409051⟩
  • Frédéric Cazals, Aditya Parameswaran, Sylvain Pion. Robust Construction of the Three-Dimensional Flow Complex. ACM Symposium on Computational Geometry (SCG), Jun 2008, Washington, United States. ⟨inria-00344962⟩
  • Andreas Meyer, Sylvain Pion. FPG: A code generator for fast and certified geometric predicates. Real Numbers and Computers, Jun 2008, Santiago de Compostela, Spain. pp.47-60. ⟨inria-00344297⟩
  • Pedro de Castro, Sylvain Pion, Monique Teillaud. Exact and efficient computations on circles in CGAL. 23rd European Workshop on Computational Geometry, 2007, Graz, Austria. ⟨hal-02196933⟩
  • Sylvain Pion, Andreas Fabri. A Generic Lazy Evaluation Scheme for Exact Geometric Computations. Library Centric Software Design (LCSD), Oct 2006, Portland, Oregon, United States. ⟨inria-00344960⟩
  • Guillaume Melquiond, Sylvain Pion. Formal certification of arithmetic filters for geometric predicates. 17th IMACS World Congress, 2005, Paris, France. ⟨inria-00344518⟩
  • Ioannis Emiris, Athanasios Kakargias, Sylvain Pion, Monique Teillaud, Elias P. Tsigaridas. Towards an Open Curved Kernel. ACM Symposium on Computational Geometry, Jun 2004, New York, United States. pp.438-446. ⟨inria-00344433⟩
  • Lutz Kettner, Kurt Mehlhorn, Sylvain Pion, Stefan Schirra, Chee Yap. Classroom Examples of Robustness Problems in Geometric Computations. European Symposium on Algorithms (ESA), Sep 2004, Bergen, Norway. pp.702-713. ⟨inria-00344515⟩
  • Hervé Brönnimann, Guillaume Melquiond, Sylvain Pion. The Boost Interval Arithmetic Library. Real Numbers and Computers, 2003, Lyon, France. pp.65-80. ⟨inria-00348711⟩
  • Sylvain Pion, Chee Yap. Constructive Root Bound for k-Ary Rational Input Numbers. 19th Annual ACM Symposium on Computational Geometry (SCG), Jun 2003, San Diego, California, United States. pp.256-263. ⟨inria-00348715⟩
  • Olivier Devillers, Sylvain Pion. Efficient Exact Geometric Predicates for Delaunay Triangulations. Proceedings of the 5th Workshop on Algorithm Engineering and Experiments, Jan 2003, Baltimore, Maryland, United States. pp.37-44. ⟨inria-00344517⟩
  • Susan Hert, Michael Hoffmann, Lutz Kettner, Sylvain Pion, Michael Seel. An Adaptable and Extensible Geometry Kernel. Workshop on Algorithm Engineering, Aug 2001, Aarhus, Denmark. pp.79-90, ⟨10.1007/3-540-44688-5⟩. ⟨inria-00344964⟩
  • Olivier Devillers, Sylvain Pion, Monique Teillaud. Walking in a Triangulation. Proceedings of the 17th Annual Symposium on Computational Geometry, Jun 2001, Boston, United States. pp.106-114, ⟨10.1145/378583.378643⟩. ⟨inria-00344519⟩
  • Jean-Daniel Boissonnat, Frédéric Cazals, Tran Kai Frank Da, Olivier Devillers, Sylvain Pion, et al.. Programming with CGAL: the example of triangulations. 8th Annual Video Review of Computational Geometry, 15th ACM Symposium on Computational Geometry (SCG), Jun 1999, Miami Beach, Florida, United States. ⟨inria-00348713⟩
  • Sylvain Pion. Interval Arithmetic: an efficient implementation and an application to computational geometry. Workshop on Applications of Interval Analysis to systems and Control (MISC), Feb 1999, Girona, Spain. ⟨inria-00344513⟩
  • Hervé Brönnimann, Christoph Burnikel, Sylvain Pion. Interval Arithmetic Yields Efficient Dynamic Filters for Computational Geometry. 14th Annual ACM Symposium on Computational Geometry (SCG), Jun 1998, Minneapolis, United States. pp.165-174. ⟨inria-00344516⟩
  • Hervé Brönnimann, Ioannis Emiris, Victor Y. Pan, Sylvain Pion. Computing exact geometric predicates using modular arithmetic with single precision. ACM Symposium on Computational Geometry (SCG), Jun 1997, Nice, France. pp.174-182. ⟨inria-00344963⟩
  • Hervé Brönnimann, Sylvain Pion. Exact rounding for geometric constructions. Scientific Computing, Computer Arithmetic and Validated Numerics (SCAN), 1997, Lyon, France. ⟨inria-00344403⟩

Reports13 documents

  • Augustin Chevallier, Sylvain Pion, Frédéric Cazals. Hamiltonian Monte Carlo with boundary reflections, and application to polytope volume calculations. [Research Report] RR-9222, INRIA Sophia Antipolis, France. 2018. ⟨hal-01919855v2⟩
  • Pierre Alliez, Christophe Delage, Menelaos Karavelas, Sylvain Pion, Monique Teillaud, et al.. Delaunay Tessellations and Voronoi Diagrams in CGAL. [Research Report] INRIA Sophia Antipolis - Méditerranée; University of Crete. 2010. ⟨hal-01421021⟩
  • Vicente Batista, David Millman, Sylvain Pion, Johannes Singler. Parallel Geometric Algorithms for Multi-Core Computers. [Research Report] RR-6749, INRIA. 2008, pp.30. ⟨inria-00343804⟩
  • Guillaume Melquiond, Sylvain Pion. Directed Rounding Arithmetic Operations in C++. [Research Report] RR-6757, INRIA. 2008, pp.11. ⟨inria-00345094⟩
  • Ankit Gupta, Pierre Alliez, Sylvain Pion. Principal Component Analysis in CGAL. [Research Report] RR-6642, INRIA. 2008, pp.13. ⟨inria-00327027⟩
  • Pedro de Castro, Sylvain Pion, Monique Teillaud. Exact and efficient computations on circles in CGAL and applications to VLSI design. [Research Report] RR-6091, INRIA. 2007, pp.14. ⟨inria-00123259v2⟩
  • Sylvain Pion, Andreas Fabri. A Generic Lazy Evaluation Scheme for Exact Geometric Computations. [Research Report] RR-5966, INRIA. 2006, pp.23. ⟨inria-00089229v2⟩
  • Sylvain Pion, Guillaume Melquiond, Hervé Brönnimann. A proposal for the C++ standard : Bool_set, multi-valued logic. [Research Report] RR-5967, INRIA. 2006, pp.22. ⟨inria-00089230v2⟩
  • Hervé Brönnimann, Guillaume Melquiond, Sylvain Pion. A Proposal to add Interval Arithmetic to the C++ Standard Library. [Research Report] RR-5646, INRIA. 2006. ⟨inria-00071231⟩
  • Olivier Devillers, Sylvain Pion. Efficient Exact Geometric Predicates for Delaunay Triangulations. RR-4351, INRIA. 2002. ⟨inria-00072237⟩
  • Susan Hert, Michael Hoffmann, Lutz Kettner, Sylvain Pion, Michael Seel. An Adaptable and Extensible Geometry Kernel. RR-4270, INRIA. 2001. ⟨inria-00072317⟩
  • Olivier Devillers, Sylvain Pion, Monique Teillaud. Walking in a triangulation. RR-4120, INRIA. 2001. ⟨inria-00072509⟩
  • Hervé Brönnimann, Ioannis Z. Emiris, Victor Y. Pan, Sylvain Pion. Computing Exact Geometric Predicates Using Modular Arithmetic with Single Precision. RR-3213, INRIA. 1997. ⟨inria-00073476⟩

Theses1 document

  • Sylvain Pion. De la géométrie algorithmique au calcul géométrique. Modélisation et simulation. Université Nice Sophia Antipolis, 1999. Français. ⟨tel-00011258⟩