## Daniel Porumbel
Associate professor/maître de conférences |

I am interested in:

- column generation, large-scale mixed/integer programs and exact methods in combinatorial optimization [S1,S2,J2].
In particular, I worked on techniques that derive
**dual bounds**by exploiting the structure of Column Generation models (e.g., the Gilmore-Gomory model or other extended formulations usually optimized by Column Generation). Such techniques include: constraint aggregation [S2], dual feasible functions [J2], ray projections in the dual polytope [S1]. In many cases, the goal is to generate faster or better bounds compared to the Lagrangian bounds more often used during Column Generation. -
**primal bounds**using meta-heuristic algorithms for very hard large problems [J1,J3,J5,J6,C1,C3-C6]. For instance, I worked on the idea of guiding search algorithms using distances between candidate solutions [J1,C1,C5,J6] or classification techniques (see the Simon Régnier prize, section Scientific Awards/Medals below).

I have applied such techniques to different problems: Graph-Coloring [J1,J6,C1,C3-C6], Arc-Routing [S1,J2], Cutting-Stock [S1,S2,J2], Isomorphism [J3,C2], MaxMin Diversity [J5], p-median [J2].

[S1] D. Porumbel,
Ray Projection for Optimizing Polytopes with Prohibitively Many Constraints in
Set-Covering Column Generation,

*Mathematical Programming* status: major revison,
revised pdf
code source.

[S2] D. Porumbel, François Clautiaux,
Convergent Dual Bounds Using an Aggregation of Set-Covering Constraints for Capacitated Problems,

*Informs Journal of Computing* status: invitation to re-submit,
pdf draft

[J1] D. Porumbel, J-K. Hao and P. Kuntz,
A Search Space "Cartography" for Guiding Graph Coloring Heuristics.
*Computers & Operations Research*, 37(4):769-778, 2010.
(pdf draft, doi)
Elsevier©

[J2] D. Porumbel, Gilles Goncalves,
Using Dual Feasible Functions to Construct Fast Lower Bounds for Routing and Location Problems
pdf, *Discrete Applied Mathematics*, in press
(doi)
Elsevier©

[J3] D. Porumbel.
Isomorphism Testing using Polynomial-Time Graph Extensions.
*Journal of Mathematical Modelling and Algorithms*, 10(2):119-143, 2011
(pdf draft, doi, isomorphism program GI-Ext)
Springer©

[J4] D. Porumbel, J-K. Hao and P. Kuntz.
An Efficient Algorithm for Computing the Distance Between Close Partitions.
*Discrete Applied Mathematics*, 159(1):53-59, 2011.
(pdf draft, doi)
Elsevier©

[J5] D. Porumbel, J-K. Hao, F. Glover.
A Simple and Effective Algorithm for the MaxMin Diversity Problem.
*Annals of Operations Research*, 186 (1):275-293, 2011.
(pdf, doi, program source code)
Springer©

[J6] D. Porumbel, J-K. Hao and P. Kuntz.
An Evolutionary Approach with Diversity Guarantee and Well-Informed Grouping Recombination for Graph Coloring,
*Computers & Operations Research*, 37(10):1822-1832, 2010.
(pdf draft, doi)
Elsevier©

[J7] D. Porumbel, J-K. Hao and P. Kuntz.
Informed Reactive Tabu Search for Graph Coloring.
*Asia Pacific Journal of Operations Research*, 30(4),
pp. 1350010, 2013
World Scientific Publishing©

[C1] D. Porumbel, J-K. Hao and P. Kuntz,
Spacing Memetic Algorithms. In proceedings of *GECCO 2011, GA track*, 1061-1068. ACM. (pdf draft, slides)

[C2] G. Audemard, C. Lecoutre, M. S. Modeliar, G. Goncalves, D. Porumbel
Scoring-based Neighborhood Dominance for the Subgraph Isomorphism Problem.
The 20th International Conference on
Principles and Practice of
*Constraint Programming (CP 2014)*

[C3] Philippe Galinier, Jean-Philippe Hamiez, Jin-Kao Hao, Daniel Porumbel,
Recent advances in graph vertex coloring, In I. Zelinka, V. Snasel, A. Abraham (eds.), *Handbook of Optimization*, Springer© (Intelligent Systems Series)

[C4] D. Porumbel, J-K. Hao and P. Kuntz,
Diversity Control and Multi-Parent Recombination for Evolutionary Graph Coloring Algorithms.
Evocop 2009 (*9th European Conference on Evolutionary Computation in Combinatorial Optimisation*, Tübingen, Germany), LNCS 5482: 121-132, 2009.
(ps, pdf) Springer©
* among the three best paper nominees*

[C5] D. Porumbel, J-K. Hao and P. Kuntz,
Position-Guided Tabu Search for Graph Coloring.
Accepted for the post-proceedings of LION 2009 (*Learning and Intelligent OptimizatioN * conference, Trento, Italy), LNCS 5851:148-162, 2009.
(paper draft, slides) Springer©

[C6] D. Porumbel, J-K. Hao and P. Kuntz,
A study of evaluation functions for the graph K-coloring problem.
Selected papers from the *8th International Conference on Artificial Evolution* (Tours, France),
LNCS 4926: 124-135, 2008.
(ps, pdf)
Springer©

[E1] D. Porumbel, Prize-Collecting Set-Covering With Submodular Pricing (pdf). Faced to this reality, I need more time for reflexion before writing more on it or re-submit.

[E2] D. Porumbel, Revisiting the bijection between planar maps and well labeled trees (pdf). This is really expository work, providing altenative arguments and correcting a slight error from a proof of a 1980's article.

More[+] (Seminars, theses)

I received the __Simon Régnier__ prize in 2011. This prize is awarded each year by the "Société
Francophone de Classification" (French-speaking Classification Society) to a researcher of maximum
35 years with a PhD thesis on classification. (slides)

Nominated for Best Paper Award (3 papers selected among more than 50), EvoCOP 2009

Bronze medal at the 41st International Mathematical Olympiad, a problem-solving competition with contestants from almost 100 countries (ranked 2nd in the qualification rounds of Romania), South Korea, 2000

Diploma for Academic Excellence of Romania's President Emil Constantinescu, 2000

I accepted review invitations from the editorial board of several journals, including:
*Journal of Artificial Intelligence Research* (open access, AAAI press),
*The Computer Journal* (Oxford University Press),
*IEEE Transactions on Evolutionary Computation * (IEEE Computer Society)
*Computers & Mathematics with Applications* (Elsevier),
*Information Processing Letters* (Elsevier),
*Engineering Applications of Artificial Intelligence* (Elsevier). I am in the program committee
of Evocop 2012, Evocop 2013, Evocop 2014. I serve as a "ECOM PC member" at Gecco 2013 and Gecco
2104.
Indirectly, I accepted writing reviews for papers (e.g., as a sub-reviewer) submitted to various conferences (e.g., ICTAI, CEC, GECCO, MOSIM).

I created a Graph Coloring Library with the results (upper bounds) of the best algorithms on all instances from the second DIMACS Implementation Challenge. I started this work during my PhD thesis.

I advised a few master theses: Ben Ibrahima Badji (Meta-heuristics for the Arc-Routing Problem, with T. Hsu, H. Allaoui, G. Goncalves, 2014); Hubert Arnoux (A tool of visualisation techniques for local search methods, with J-K Hao, P. Kuntz, 2012); Fahrur Rozi and Mochammad Luthfi (Airport passenger flow simulation in Quest and Arena and resource allocation optimization), with G. Gonvalves, 2011).

- University of Artois (IUT Béthune), around
**250 hours per year, responsability of a dozen of 30-hours modules**since 2010: Network Programming (sockets), Event-Driven Programming (Swing graphical interface), Operating Systems, Security, Advanced Algorithms
▼ - *Programmation événementielle et réseaux: cours (sockets, fils d'exécutions, événements, interface graphique Swing, etc.)
- *Programmation orientée objets: cours , tp1 (classes de bases, une première interface graphique), tp2 (fenêtres Swing, animations 2D basiques)
- *Sécurité cours (exemples d'attaques, cryptographie, routage et filtrage à l'aide d'iptables, etc)
- *Algorithmique avancée cours (exemples de problèmes algorithmiques, complexités, bases mathématiques de la cryptographie, etc)
- *Système d'exploitation et programmation système cours (fils d'exécutions, signaux, bash), un tp sur de commandes utiles Bash
- Bases de la programmation
- *Consolidation des bases de la programmation un mini-projet sur une recherche locale pour un problème d'ingénierie de trafic réseau, TP1 (tableaux, calculs de séries, 𝛑²/6)
- University of Angers (Computer Science department), 2008 - 2009, responsability of the Networks module, assisting with many other problem and computer classes (Artificial Ingelligence, Web Programming, Compilation) More[+] (2008-2010)
- Univeristy of Nantes (Ecole Polytechnique), 2006 - 2008, assisting in "Metaheuristics and Optimisation" More[+] (2006-2008)
- Faculty of Automatic Control and Computers (University Politehnica of Bucharest) 2004-2006, teaching assistant on a dozen of subjects (e.g., Artificial Intelligence, OpenGL Computer Graphics, Algorithm Design and Complexity) More[+] (2004-2006)