|I did do a bit
This is our key philosophy.txt, the only possible fuel for all work on this page
From an implementation detail to an unlimited manifesto on the artificial&injurious distance between theory and real computing.htm
On the tragic side of working for the truth.pdf
Demystifying the characterizations of SDP matrices in mathematical programming.pdf:
I wrote this introduction to SDP (semipositive definite) programming becase I found no other introduction
that targets the same public.
This work is intended to be accessible to anybody who learned (a lot of) maths in the past but does
not work full time in (SDP) matrix theory.
For instance, the eigen-decompostion is not a pre-requisite unlike in most other SDP
introductions; I even provide two proofs to gain full insight and to learn related properties.
All in 100 pages, not 700.
The text is self-contained in a strong sense,
i.e., everything is proven from
scratch, because I can't stand taking things for granted: no secret,
no empty jargon, no more formula out of the blue, no longer my(s)thification.
Daniel Porumbel, Demystifying (a light variant of) the Karush-Kuhn-Tucker conditions with full proofs for the linear program with logarithmic barrier used in Interior Point Algorithms.pdf : I wrote this because I plan to attack Interior Point Algorithms (IPMs); my goal is to implement IPMs to solve linear programs with prohibitively many constraints (and later SDP programs). No joke; all I need is time, God willing.
Daniel Porumbel, Further experiments and insights on Projective Cutting-Planes pdf (technical report of CEDRIC CS Lab : CEDRIC-19-4550)
Daniel Porumbel, Igor Machao, El-Ghazali Talbi, Using an Exact Bi-Objective Decoder in a Memetic Algorithm for Arc-Routing (and Other Decoder-Based) Problems
[J1] Daniel Porumbel, Projective Cutting-Planes, SIAM Journal on Optimization, 30(1): 1007-1032, 2020 (pdf draft, slides, source code, youtube 20 minutes, youtube 40 minutes, doi link)
[J2] Daniel Porumbel, Ray Projection for Optimizing Polytopes with Prohibitively Many Constraints in Set-Covering Column Generation, Mathematical Programming 155(1): 147-197, 2016 (pdf draft, source code), Springer©, doi link
[J3] Daniel Porumbel, From the Separation to the Intersection Sub-problem in Benders Decomposition Models with Prohibitively-Many Constraints, Discrete Optimization, 29:148-173, 2018 (pdf draft, source code, slides [fr]),
[J4] Daniel Porumbel, François Clautiaux, Convergent Dual Bounds Using an Aggregation of Set-Covering Constraints for Capacitated Problems, INFORMS Journal of Computing, 29(1):170-184, 2017. (pdf draft, slides, supplement)
[J5] Daniel Porumbel, J-K. Hao, Distance-Guided Local Search, Journal of Heuristics, 2020, 26(5):711-741. (pdf draft)
[J6] D. C. Porumbel, J-K. Hao, P. Kuntz, A Search Space "Cartography" for Guiding Graph Coloring Heuristics. Computers & Operations Research, 37(4):769-778, 2010. (pdf draft), Elsevier©, doi link
[J7] Daniel Porumbel, Prize-Collecting Set Multi-Covering With Submodular Pricing, International Transactions in Operational Research, 25 (4):1221-1239, 2018, (pdf draft), Wiley-Blackwell©
[J8] D. Porumbel, G. Goncalvez, H. Allaoui; T. Hsu;
Arc-Routing via Column Generation and Iterated Local Search in a Permutation Set-Covering Framework,
European Journal of Operational Research 256(2):349-367, 2017 pdf draft, slides Roadef 2015 (French OR congress) Elsevier© ,
[J9] D. Porumbel, G. Goncalves, Using Dual Feasible Functions to Construct Fast Lower Bounds for Routing and Location Problems, Discrete Applied Mathematics, 196: 83-99, 2015, (pdf draft), Elsevier©, doi
[J10] Daniel Porumbel. Isomorphism Testing using Polynomial-Time Graph Extensions. Journal of Mathematical Modelling and Algorithms, 10(2):119-143, 2011 (pdf draft, slides [fr], isomorphism program GI-Ext), Springer©, doi
[J11] D. C. Porumbel, J-K. Hao, P. Kuntz. An Efficient Algorithm for Computing the Distance Between Close Partitions. Discrete Applied Mathematics, 159(1):53-59, 2011, (pdf draft), Elsevier©, doi
[J12] D. C. Porumbel, Jin-Kao Hao, Fred Glover, A Simple and Effective Algorithm for the MaxMin Diversity Problem. Annals of Operations Research, 186 (1):275-293, 2011, (pdf draft, source code), Springer©, doi
[J13] D. C. Porumbel, J-K. Hao, 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), Elsevier©, doi
[J14] Nathalie Helal, Frédéric Pichon, D. Porumbel, David Mercier, Éric Lefèvre. The capacitated vehicle routing problem with evidential demands, International Journal of Approximate Reasoning 95:124-151, 2018 (pdf) Elsevier©
[J15] D. C. Porumbel, J-K. Hao, P. Kuntz. Informed Reactive Tabu Search for Graph Coloring. Asia Pacific Journal of Operations Research, 30(4), pp. 1350010, 2013 (pdf draft), World Scientific Publishing©
[C1] D. Porumbel, J-K. Hao, 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, 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, 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, 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, Revisiting the bijection between planar maps and well labeled trees (pdf). In this work, we provide alternative arguments and correct a slight error of a graph theory article from around 1970s/1980s.
[PhD] D. Porumbel, PhD thesis,
dedicated to my grandfather.
More[+] (Seminars, theses)
When I was a kid, I really liked mathematics problem-solving contests and I even went to the international level, see below. Even later, in 2011, I could receive a PhD prize called Simon Régnier awarded by the "Société Francophone de Classification" (French-speaking Classification Society), see these slides. I now believe that science prizes make sense for enthusiastic kids or students. For a grown-up man, thinking about prizes (even up to the Nobel one) is short-sighted. The only prize I dream of is you -- any public reading my work. Yes, all I want is you, I mean you and me wishing on the same star.
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 different journals since 2017: INFORMS Journal of Computing, Computational Optimization and Applications, European Journal of Operational Research, Operational Research , IEEE Transactions on Cybernetics, Computers and Operations Research, Transportation Research part E, Engineering Optimization, Theoretical Computer Science, Discrete Applied Mathematics, Journal of Computational Science. Before 2017, I performed reviews for journals like: Canadian Mathematical Bulletin, Journal of Artificial Intelligence Research, The Computer Journal, IEEE Transactions on Evolutionary Computation, European Journal of Operations Research, Computers and Operations Research, Evolutionary Computation, Computers & Mathematics with Applications, Information Processing Letters, Expert Systems and Applications, Engineering Applications of Artificial Intelligence, Computing. I was in the program committee of different conferences (Evocop 2012, Evocop 2013, Evocop 2014, Evocop 2019, Evocop 2020, Evocop 2021, Gecco Ecom 2013, Gecco Ecom 2014, Gecco Ecom 2015, Gecco Ecom 2016, Gecco Ecom 2017, Gecco Ecom 2018, Gecco Ecom 2019, Gecco Ecom 2020, Gecco Ecom 2021, Ecta 2019).
I (co-)advised a PhD thesis: Nathalie Helal, An evidential answer for the capacitated vehicle routing problem with uncertain demands, defended in 2017 (main adviser: Eric Lefèvre, second adviser Frédéric Pichon, collaboration with David Mercier). I adivised some master theses along the years: Thomas Ridremont (Robust optimisation of wiring in renewable-energy installations, with Marie-Christine Costa and Cédric Bentz, 2015); Hubert Arnoux (A tool of visualisation techniques for local search methods, with J-K Hao, P. Kuntz, 2012); Junlin Zhu (Mathematical Programming Models for Graph Isomorphism, with Amélie Lambert, 2015); Ben Ibrahima Badji (Meta-heuristics for the Arc-Routing Problem, with T. Hsu, H. Allaoui, G. Goncalves, 2014); Fahrur Rozi and Mochammad Luthfi (Airport passenger flow simulation in Quest and Arena and resource allocation optimization, with G. Gonvalves, 2011).
I created a library for Graph Coloring Benchmarking during my PhD thesis.