
Sylvain Pion
Former Researcher in Computer Science in the
Geometrica group
Since January 2011, I am on leave from INRIA.
Email :
 FirstName.LastName@inria.fr

Skype :
 spion315

Networks :



Research
I am interested in computer programming of geometric algorithms.
Mesh generation and the other algorithms developed by my coworkers from
Geometrica are of particular interest, as well
as any computational geometry algorithm you may find for example in
CGAL.
Programming issues of interest are: the efficiency of basic
certified
numerical routines (the geometric predicates and
constructions which are so critical to the robustness of geometric
algorithms), formal proofs of algorithms, parallel
algorithms and compact memory representations of data
structures. I am also interested in compiler optimizations and
programming languages, especially C++. Another important
direction of programming is the maintainability of large code bases
like CGAL, which triggers research on finding
concepts with broad applicability to help code factorization and
understandability, within the generic programming paradigm.
Publications
Below are some of my recent publications, and here is
the complete list.

A Generic Lazy Evaluation Scheme for Exact Geometric Computations
S. Pion and A. Fabri. Science of Computer Programming, 2011.

Parallel Geometric Algorithms for MultiCore Computers
V. H. F. Batista, D. L. Millman, S. Pion and J. Singler. CGTA, 2010.

Directed Rounding Arithmetic Operations in C++
G. Melquiond and S. Pion. ISO, WG21 document number
N2811, 2008.
 Robust construction
of the threedimensional flow complex
F. Cazals, A. Parameswaran and S. Pion. SoCG, 2008.
 FPG: A code
generator for fast and certified geometric predicates
A. Meyer and S. Pion. RNC, 2008.
 Classroom Examples of
Robustness Problems in Geometric Computations
L. Kettner, K. Mehlhorn, S. Pion, S. Schirra and C. Yap. CGTA, 2008.
Collaborative projects
Standardization
In connection to my research, I participate to the work of the following standardization committees:
 WG21 : the ISO
working group for the standardization of the C++ programming language.
Here is a list of my C++ work.
 IEEE1788 :
standardization of interval arithmetic.
Software
Most of my developments are done around CGAL,
of which I am a member of the editorial
board (which I chaired from February 2006 to June 2010).
Watch the general presentation video !
 CGAL : I significantly contributed to:
 the 2D/3D triangulations,
 the geometric kernel,
 the arithmetic kernel (floatingpoint filters...),
 plenty of other stuff,
 the Python and
Scilab bindings,
 the overall technical direction of the project through the CGAL editorial board,
 the maturation of key parts which allowed the creation of
GeometryFactory in
2003, the company distributing CGAL, with which I am still
frequently in contact.
 Boost : I am a coauthor of the
Boost.Interval library.
 CORE : I implemented
improvements to the root bound mechanism for floatingpoint input, and other optimizations.
 GCC : I implemented a few optimizations
helping interval arithmetic (some expression transformations).
 ♕ Nqueens problem :
I used to hold the world record for N=2123 using a distributed program.
 Miscellaneous: the Linux kernel, where I once added support for large swap
areas, and some other old programs.
Program committees and editorial responsibilities
Teaching
 Some courses I gave.
 Jury : I was member of the jury at the entrance examination of the
ENS (algorithmic and programming oral
exam), from 2007 to 2009.
Other responsibilities
 I was a member of the
CDL, the local
committee dealing with software development from 2004 to 2007.
 JeanPaul Rigault and I organized a
WG21 Meeting
in Sophia Antipolis, in June 2008.
Miscellaneous
 What do I do in my free time ?
I like gardening, paragliding/flying, rockclimbing, biking...
See also some bike benchmarks.
 Some old archives of the mailinglist
stdinterval (2006),
now hosted here.
 Some old information about the
FFJM
(French Federation of Mathematical and Logical games).