Welcome to my personal webpage. My name is Dimitrios Letsios and I am a postdoctoral research associate in the Computational Optimisation Group at Imperial College London, collaborating with Ruth Misener in the context of the EPSRC project "UPSI^2: Uncertainty-Aware Planning and Scheduling in the Process Industries".

Research Interests

• Scheduling and graph problems
• Combinatorial optimization, algorithms with performance guarantees, mixed-integer linear programming
• Energy efficient computing, efficient big data processing
• Optimization problems in process systems engineering
• Data-driven optimization and explainable artificial intelligence

Employment, Visits and Studies

• Postdoctoral Research Associate. Computational Optimisation Group. Imperial College London (UK). July 2016 - present.
• Teaching and Research Assistant. Combinatorics, Optimization, and Algorithms for Telecommunications Group. INRIA Sophia Antipolis - Méditerranée and Université Nice - Sophia Antipolis (France). September 2015 - July 2016.
• Postdoctoral Researcher. Chair of Theoretical Computer Science. Technische Universität München (Germany). June 2014 - July 2015.
• Teaching and Research Assistant. Operational Research Group. Université Pierre et Marie Curie (France). September 2013 - May 2014.
• Visiting Researcher. University of Pittsburgh (USA). November 2010 - December 2010.
• Ph.D. in Computer Science, Université d'Evry Val d'Essonne (France), February 2010 - October 2013.
• M.Sc. and B.Sc. in Computer Science, Athens University of Economics and Business (Greece), September 2004 - January 2010.

Curriculum Vitae and Social Media Profiles

• Academic CV  
  
• GitHub  
• Google Scholar  
• LinkedIn  

Publications

Recent Manuscripts

• D. Letsios, R. Misener. Exact Lexicographic Scheduling and Approximate Rescheduling. 2018.    
  
• M. Mistry, D. Letsios, R. Misener, G. Krennrich, R. M. Lee. Mixed-Integer Convex Nonlinear Optimization with Gradient-Boosted Trees Embedded. 2018.    
  
• J. C. Bermond, N. Cohen, D. Coudert, D. Letsios, I. Milis, S. Pérennes, V. Zissimopoulos. Bin Packing with Colocations. 2018.    
  

International Refereed Journals

• E. Angel, E.Bampis, F. Kacem, D. Letsios. Speed Scaling on Parallel Processors with Migration. Journal of Combinatorial Optimization (accepted), 2018.    
  
• D. Letsios, G. Kouyialis, R. Misener. Heuristics with Performance Guarantees for the Minimum Number of Matches Problem in Heat Recovery Network Design. Computers and Chemical Engineering 113, p.57-85, 2018.    
  
• E. Bampis, A. Kononov, D. Letsios, G. Lucarelli, M. Sviridenko. Energy-Efficient Scheduling and Routing via Randomized Rounding. Journal of Scheduling 21(1), p.35-51, 2018.    
  
• S. Albers, E. Bampis, D. Letsios, G. Lucarelli, R. Stotz. Scheduling on Power-Heterogeneous Processors. Information and Computation 257, p. 22-33, 2017.    
  
• E. Angel, E. Bampis, V. Chau, D. Letsios. Throughput Maximization for Speed-Scaling with Agreeable Deadlines. Journal of Scheduling 19(6), p. 619-625, 2016.    
  
• E. Bampis, D. Letsios, I. Milis, G. Zois. Speed Scaling for Maximum Lateness. Theory of Computing Systems 58(2), p. 304-321, 2016.    
  
• E. Bampis, A. Kononov, D. Letsios, G. Lucarelli, I. Nemparis. From Preemptive to Non-preemptive Speed-Scaling Scheduling. Discrete Applied Mathematics 181, p. 11-20, 2015.    
  
• E. Bampis, D. Letsios, G. Lucarelli. Green Scheduling, Flows and Matchings. Theoretical Computer Science 579, p. 126-136, 2015.    
  
• N. Barcelo, D. Cole, D. Letsios, M. Nugent, K. Pruhs. Optimal Energy Trade-off Schedules. Journal of Sustainable Computing: Informatics and Systems 3(3), p. 207-217, 2013.    
  
• E. Bampis, D. Letsios, G. Lucarelli, V. Markakis, I. Milis. On Multiprocessor Temperature-Aware Scheduling Problems. Journal of Scheduling 16(5), p. 529-538, 2013.    
  

International Refereed Conferences with Proceedings

• K. Cyras, D. Letsios, R. Misener, F. Toni. Argumentation for Explainable Scheduling. AAAI Conference on Articial Intelligence (AAAI), 2019 (accepted for presentation).
• J.C. Bermond, N. Cohen, D. Coudert, D. Letsios, I. Milis, S. Perennes, V. Zissimopoulos. Bin Packing with Colocations. Workshop on Approximation and Online Algorithms (WAOA) , p. 41-54, LNCS 10138, Springer, 2016.    
  
• S. Albers, E. Bampis, D. Letsios, G. Lucarelli, R.Stotz. Scheduling on Power-Heterogeneous Processors. Latin American Theoretical Informatics Symposium (LATIN) , p. 41-54, LNCS 9644, Springer, 2016.    
  
• E. Bampis, D. Letsios, G. Lucarelli. Speed Scaling with No Preemptions. International Symposium on Algorithms and Computation (ISAAC) , p. 259-269, LNCS 8889, Springer, 2014.    
  
• E. Bampis, V. Chau, D. Letsios, G. Lucarelli, I. Milis, G. Zois. Energy Efficient Scheduling of MapReduce Jobs. International European Conference on Parallel Processing (Euro-Par), p. 198-209, LNCS 8632, Springer, 2014.    
  
• E. Bampis, D. Letsios, G. Lucarelli. A Note on Multiprocessor Speed Scaling with Precedence Constraints. ACM Symposium on Parallelism in Algorithms and Architectures (SPAA), p. 138-142, ACM, 2014.    
  
• E. Bampis, A. Kononov, D. Letsios, G. Lucarelli, M. Sviridenko. Energy Efficient Scheduling and Routing via Randomized Rounding. Conference on Foundations of Software Technology and Theoretical Computer Science (FSTTCS) , p. 449-460, LIPIcs 24, Schloss Dagstuhl, 2014.    
  
• E. Bampis, A. Kononov, D. Letsios, G. Lucarelli, I. Nemparis. From Preemptive to Non-preemptive Speed-Scaling Scheduling. International Computing and Combinatorics Conference (COCOON), p. 134-146, LNCS 7936, Springer, 2013.    
  
• E. Bampis, V. Chau, D. Letsios, G. Lucarelli, I. Milis. Energy Minimization via a Primal-Dual Algorithm for a Convex Program. International Symposium on Experimental Algorithms (SEA), p. 366-377, LNCS 7933, Springer, 2013.    
  
• E. Angel, E. Bampis, V. Chau, D. Letsios. Throughput Maximization for Speed-Scaling with Agreeable Deadlines. Conference on Theory and Applications of Models of Computation (TAMC) , p. 10-19, LNCS 7876, Springer, 2013.    
  
• E. Bampis, D. Letsios, G. Lucarelli. Green Scheduling, Flows and Matchings. International Symposium on Algorithms and Computation (ISAAC), p. 106-115, LNCS 7676, Springer, 2012.    
  
• E. Angel, E. Bampis, F. Kacem, D. Letsios. Speed Scaling on Parallel Processors with Migration. International European Conference on Parallel Processing (Euro-Par) , p. 128-140, LNCS 7484, Springer, 2012.    
  
• E. Bampis, D. Letsios, I. Milis, G. Zois. Speed Scaling for Maximum Lateness. International Computing and Combinatorics Conference (COCOON), p. 25-36, LNCS 7434, Springer, 2012.    
  
• N. Barcelo, D. Cole, D. Letsios, M. Nugent, K. Pruhs. Optimal Energy Trade-off Schedules. International Green Computing Conference (IGCC) , p. 1-10, IEEE, 2012.    
  
• E. Bampis, D. Letsios, G. Lucarelli, V. Markakis, I. Milis. On Multiprocessor Temperature-Aware Scheduling Problems. Joint Conference of International Frontiers of Algorithmics Workshop and International Conference on Algorithmic Aspects of Information and Management (FAW-AAIM), p. 149-160, LNCS 7285, Springer, 2012.    
  

Conferences / Workshops with Abstracts

• D. Letsios, G. Kouyialis, R. Misener. Approximation Algorithms for Process Systems Engineering. European Symposium on Computer Aided Process Engineering (ESCAPE) , volume 43, p. 565-566, 2018.
• D. Letsios, R. Misener. Exact Lexicographic Scheduling and Approximate Rescheduling. International Symposium on Mathematical Programming (ISMP) , 2018.
• D. Letsios, G. Kouyialis, R. Misener. Heuristics with Performance Guarantees for the Minimum Number of Matches Problem in Heat Recovery Network Design. IMA Conference on Numerical Linear Algebra and Optimization , 2018.
• D. Letsios, R. Misener. On Exact Lexicographic Optimization and Approximate Recovery Strategies in Two-Stage Robust Makespan Scheduling. New Challenges in Scheduling Theory Workshop, Aussois, 2018.
• D. Letsios, G. Kouyialis, R. Misener. Heuristics with Performance Guarantees for the Minimum Number of Matches Problem in Heat Recovery Network Design. Congrès Annuel de la Société Francaise de Recherche Opérationelle et d'Aide à la Décision (ROADEF) , 2018.
• D. Letsios, G. Kouyialis, R. Misener. Heuristics with Performance Guarantees for the Minimum Number of Matches Problem in Heat Recovery Network Design. Research Associate Symposium (RA Symposium), Department of Computing, Imperial College London , 2017. Awarded 2nd prize for presentation. .
• D. Letsios, R. Misener. Lexicographic Optimization for Rescheduling. IMA and OR Society Conference on Mathematics of Operational Research (IMA-OR) , 2017.
• S. Albers, E. Bampis, D. Letsios, G. Lucarelli, R. Stotz. Scheduling on Power-Heterogeneous Processors. Congrès Annuel de la Société Francaise de Recherche Opérationelle et d'Aide à la Décision (ROADEF) , 2016.
• E. Bampis, D. Letsios, G. Lucarelli. Multiprocessor Speed Scaling with Precedence Constraints. Congrès Annuel de la Société Francaise de Recherche Opérationelle et d'Aide à la Décision (ROADEF) , 2015.
• E. Bampis, A. Kononov, D. Letsios, G. Lucarelli, M. Sviridenko. Energy Efficient Scheduling and Routing via Randomized Rounding. Congrès Annuel de la Société Francaise de Recherche Opérationelle et d'Aide à la Décision (ROADEF) , 2014.
• E. Bampis, A. Kononov, D. Letsios, G. Lucarelli, M. Sviridenko. Energy Efficient Scheduling and Routing via Randomized Rounding. Workshop on Models and Algorithms for Planning and Scheduling (MAPSP) , 2013.
• E. Bampis, D. Letsios, G. Lucarelli. Ordonnancement, Flots et Couplages Verts. Congrès Annuel de la Société Francaise de Recherche Opérationelle et d'Aide à la Décision (ROADEF), 2013 .
• E. Angel, E. Bampis, F. Kacem, D. Letsios. Ordonnancement des Tâches avec Migration et Minimisation de l'Energie Consommée. Congrès Annuel de la Société Francaise de Recherche Opérationelle et d'Aide à la Décision (ROADEF) , 2012.

Posters

• D. Letsios, G. Kouyialis, R. Misener. Heuristics with Performance Guarantees for the Minimum Number of Matches Problem in Heat Recovery Network Design. SIAM IKIE Meeting, 2018. G. Kouyialis awarded best poster award.
• L. G. Papageorgiou, V. Dua, P. Parpas, W. Wieseman, R. Misener, E. N. Pistikopoulos, A. Aguirre, V. Charitopoulos, J. Silvente, D. Letsios. Uncertainty-Aware Planning and Scheduling in the Process Industries. CPSE Annual Industrial Consortium Meeting, 2017.
• M. Mistry, D. Letsios, R. Misener, G. Krennrich, R. M. Lee. Optimization with Gradient-Boosted Trees and Risk Control. CPSE Annual Industrial Consortium Meeting, 2017.
• D. Letsios, G. Kouyialis, R. Misener. Heuristics with Performance Guarantees for the Minimum Number of Matches Problem in Heat Recovery Network Design. CPSE Annual Industrial Consortium Meeting, 2017. G. Kouyialis awarded 2nd prize for poster presentation.
• D. Letsios, G. Kouyialis, R. Misener. Heuristics with Performance Guarantees for the Minimum Number of Matches in Heat Recovery Network Design. 2nd PSE@ResearchDayUK, 2017. G. Kouyialis awarded best poster prize.
• L. G. Papageorgiou, V. Dua, P. Parpas, W. Wieseman, R. Misener, E. N. Pistikopoulos, A. Aguirre, V. Charitopoulos, J. Silvente, D. Letsios. Uncertainty-Aware Planning and Scheduling in the Process Industries. CPSE Annual Industrial Consortium Meeting, 2016.

Teaching

Imperial College London

• Computational Optimization. M.Sc. Computing. Fall 2018.
• Machine Learning. M.Sc. Business Analytics. Fall 2018.

Université Nice - Sophia Antipolis

• Introduction to Computer Science. L1 Informatique. Fall 2015.
• Introduction to Programming with Python. L1 Informatique. Fall 2015, Spring 2016.
• Introduction to Web Programming with HTML and CSS. L1 Informatique. Fall 2015.
• Data Structures with Python. L2 Informatique. Fall 2015.
• Object-Oriented Programming with Java. L3 Informatique. Fall 2015.
• Probabilities and Statistics. L3 and M1 Miage. Spring 2016.

Technische Universität München

• Randomized Algorithms. M.Sc. Informatics. Fall 2014.
• Online and Approximation Algorithms. M.Sc. Informatics. Spring 2015.

Université Pierre et Marie Curie

• Introduction to Programming with C. L1 Polytech. Spring 2014.
• Data Structures with C. L2 Polytech. Fall 2013.
• Special Topics on Algorithms. L3 Informatique and M1 IAD. Spring 2014.

Université d'Evry Val d'Essonne

• Introduction to Programming with C. L2 Chimie. Fall 2010, Fall 2011.
• Introduction to Programming with Java. L1 Informatique. Fall 2012.
• Introduction to Algorithms. L3 Informatique. Spring 2012, Spring 2013.
• Graph Algorithms. L3 Informatique. Spring 2011, Spring 2012, Spring 2013.
• Mathematical Programming. M1 MOPS. Spring 2011, Spring 2012.
• Operational Research. M1 MOPS. Spring 2013.

Contact Details

  d.letsios@imperial.ac.uk
  +44 (0) 20759 43812
  Office 302, Huxley Building, 180 Queen's Gate, Kensington, SW7 2AZ, London