About
I am a postdoc in
Combinatorics and Optimization
at the
University of Waterloo,
with Ricardo Fukasawa.
I did my PhD at the
Montefiore Institute
(University of Liège),
with Quentin Louveaux.
Contact:
Room MC 6032, extension 31080, UWaterloo
poirrier montefiore.ulg.ac.be
2003  2008  :  Engineering in Electronics, University of Liège 
2008  2012  :  PhD in Applied Sciences, University of Liège 
2012  2013  :  Postdoc, University of Padova 
2013   :  Postdoc, University of Waterloo 
Research Interests
 Mixedinteger programming (cutting planes, column generation)
 Computational issues in linear algebra (direct factorization, simplex method)
 Computations and applications of combinatorial problems (vehicle routing)
 Algorithms in computational geometry (space partitioning)
Papers
(authors in alphabetical order) Q. Louveaux, L. Poirrier. "An algorithm for the separation of tworow cuts", Mathematical Programming A. 143(12):111146, 2014 (handle, doi).
 Q. Louveaux, L. Poirrier, D. Salvagnin. "The strength of multirow models", Mathematical Programming Computation. 7(2):113148, 2015 (handle, doi).
 R. Fukasawa, L. Poirrier. "Numerically safe lower bounds for the capacitated vehicle routing problem", accepted, INFORMS Journal on Computing, 2016.
 R. Fukasawa, L. Poirrier, Á. S. Xavier. "Intersection cuts for single row corner relaxations", submitted, 2016.
 R. Fukasawa, L. Poirrier, Á. S. Xavier. "The (not so) Trivial Lifting in Two Dimensions", submitted, 2016.
 R. Fukasawa, L. Poirrier. "Permutations in the factorization of linear programming bases", submitted, 2016.
PhD thesis
L. Poirrier. "Multirow approaches to cutting plane generation", October 2012, PhD thesis.Presentations
 L. Poirrier. "Parallel Processing in Mixed Integer Programming". Belgian Mathematical Programming Workshop, March 27th, 2009.
 Q. Louveaux, L. Poirrier. "A computational survey of bestcase gap closure for various relaxations". MIP 2010 poster session, July 26th, 2010.

Q. Louveaux,
L. Poirrier.
"A separation method for tworow cuts".
 Systmod seminar, ULg, November 5th, 2010.
 DEI, Università degli Studi di Padova, February 23rd, 2011.
 Belgian Mathematical Programming Workshop, April 7th, 2011.

Q. Louveaux,
L. Poirrier,
D. Salvagnin.
"The Strength of Multi Row Relaxations".
 INFORMS 2011, November 16th, 2011.
 16th Combinatorial Optimization Workshop, Aussois, January 12th, 2012.
 Belgian Mathematical Programming Workshop, March 1st, 2012.
 ISMP 2012.

L. Poirrier.
"Multirow approaches to cutting plane generation".
 PhD defense, ULg, December 18th, 2012.
 UWaterloo C&O Tutte Seminar, February 14th, 2014.
 R. Fukasawa, L. Poirrier. "Permutations in the factorization of LP bases". MIP 2014, July 23rd, 2014.
 R. Fukasawa, L. Poirrier. "Numerically safe lower bounds for the Capacitated Vehicle Routing Problem". ISMP 2015, July 16th, 2015.
Teaching
Math 115: Linear Algebra for Engineers (Spring 2015)
Course outline.Link: image manipulation with transformation matrices.
Assignment 1: questions. solutions. quiz. Due Thursday, May 14th at the tutorial.
Assignment 2: questions. solutions. quiz. Due Thursday, May 21th at the tutorial.
Assignment 3: questions. solutions. quiz. Due Thursday, May 28th at the tutorial.
Assignment 4: questions. solutions. quiz. Due Thursday, June 4th at the tutorial.
Assignment 5: questions. solutions. quiz. Due Thursday, June 11th at the tutorial.
Assignment 6: questions. solutions. quiz. Due Thursday, June 25th at the tutorial.
Assignment 7: questions. solutions. quiz. Due Thursday, July 2nd at the tutorial.
Assignment 8: questions. solutions. quiz. Due Thursday, July 9th at the tutorial.
Assignment 9: questions. solutions. quiz. Due Thursday, July 23rd at the tutorial.
Useful information for the midterm:
 Time and location: Thursday, June 18th at 1:30pm, room RCH 306.
 Additional office hours: Monday, June 15th, 2pm4pm (my office is MC 6032).
 WEEF help session: Wednesday, June 17th, 3:30pm6:30pm, room DWE 3518.
 Relevant questions from past midterms.
 A practice midterm.
 A partial list of identities and properties seen in class to do computations with vectors and matrices.
 Solutions to the midterm
Useful information for the final:
 Time and location: Monday August 10, at 4:00pm, room MC 2034.
 WEEF help session: Friday, August 7, at 1pm, room RCH 209.
 Additional office hours: Friday, August 7 after the help session (my office is MC 6032).
 Relevant questions from past finals.
 A practice final.
Tutoring at ULg (2008  2012)
See archived tutorials.Software
pxx  Modeling tools for linear optimization (C++ library): Dense: vectors, adjacency matrices, symmetric matrices
 Sparse: vectors, linear constraints, cut pools
 Modeling: linear discrete models, cplex C API wrappers
 MIP: Onerow and tworow intersection cut separators
task  a task scheduler for distributed computations (see documentation)
now  a terminalbased monthview calendar.
Older projects
Particlebased simulation
Algorithms for efficient shortrange interaction detection in particlebased simulations.Master thesis: L. Poirrier. "Simulation d'interactions dynamiques", 2008
Gemvid
J.E. Poirrier, L. Poirrier, P. Leprince, P. Maquet. "Gemvid, an open source, modular, automated activity recording system for rats using digital video" Journal of Circadian Rhythms 2006, 4:10 full text web site
Outdated version 0.6 available
here.
Version 0.8 prereleases:
a,
b,
c
J.E.'s
presentation at FOSDEM 2009:
090207gemvid.pdf