ORBEL 28

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Detailed schedule

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Thursday 30 January:

9:00-9:30Registration (Hall of Vesale Building)
9:30-10:45Plenary session (Room Vesale 023)
Welcome
Invited speaker: Gerhard Woeginger
Optimization at the second level
10:45-11:15Coffee break
11:15-12:30Parallel sessions
  TA-1: COMEX - Optimization 1
Chair: M. Schyns
Room: Vesale 023
TA-2: Software and Implementation
Chair: M. Mezmaz
Room: Vesale 020
TA-3: COMEX - Smart mobility
Chair: A. Caris
Room: Vesale 025
TA-4: Systems
Chair: P. Kunsch
Room: Pentagone 0A11
12:30-14:00Lunch (First floor of the Restaurant building)
13:30-General Assembly
14:00-15:40Parallel sessions
  TB-1: Data Analysis 1
Chair: X.Siebert
Room: Vesale 023
TB-2: Multiple Objectives
Chair: Y. de Smet
Room: Vesale 020
TB-3: Logistics
Chair: D. De Wolf
Room: Vesale 025
TB-4: COMEX - Applications to Economy
Chair: W. Brauers
Room: Pentagone 0A11
TB-5: Networks
Chair: B. Fortz
Room: Pentagone 0A07
15:40-16:10Coffee break
16:10-17:25Parallel sessions
  TC-1: Mixed-integer nonlinear programming
Chair: Y. Crama
Room: Vesale 023
TC-2: Decision Analysis 1
Chair: S. Eppe
Room: Vesale 020
TC-3: Routing
Chair: K. Sörensen
Room: Vesale 025
TC-4: Graphs
Chair: H. Mélot
Room: Pentagone 0A11
TC-5: Scheduling
Chair: S. Hanafi
Room: Pentagone 0A07
 
17:30-General Assembly (if quota not reached at 13:30)
19:30-Conference dinner

Friday 31 January
9:00-10:15Parallel sessions
  FA-1: Queuing
Chair: S. Wittevrongel
Room: Vesale 023
FA-2: Decision Analysis 2
Chair: R. Bisdorff
Room: Vesale 020
FA-3: COMEX - Optimization 2
Chair: M. Labbé
Room: Vesale 025
FA-4: Production
Chair: D. Tuyttens
Room: Pentagone 0A11
 
10:15-10:40Coffee break
10:40-12:40Plenary session (Room Vesale 023)
Invited speaker: Matthias Ehrgott
From routeplanning to scheduling and policy decisions: Applications of multiobjective optimization in transportation
ORBEL Award
Wolsey award announcement
12:40-14:00Lunch (First floor of the Restaurant building)
14:00-15:40Parallel sessions
  FB-1: Data Analysis 2
Chair: P. Fortemps
Room: Vesale 023
FB-2: Heuristics
Chair: T. Stützle
Room: Vesale 020
FB-3: COMEX - Transportation
Chair: F. Spieksma
Room: Vesale 025
FB-4: Health
Chair: G. Vanden Berghe
Room: Pentagone 0A11
 
15:40-17:00Closing: Coffee, beers and wine


Thursday 11:15-12:30 TA-1: COMEX - Optimization 1
Room Vesale 023 - Chair: M. Schyns

Thursday 11:15-12:30 TA-2: Software and Implementation
Room Vesale 020 - Chair: M. Mezmaz

Thursday 11:15-12:30 TA-3: COMEX - Smart mobility
Room Vesale 025 - Chair: A. Caris

Thursday 11:15-12:30 TA-4: Systems
Room Pentagone 0A11 - Chair: P. Kunsch

Thursday 14:00-15:40 TB-1: Data Analysis 1
Room Vesale 023 - Chair: X.Siebert

Thursday 14:00-15:40 TB-2: Multiple Objectives
Room Vesale 020 - Chair: Y. de Smet

Thursday 14:00-15:40 TB-3: Logistics
Room Vesale 025 - Chair: D. De Wolf

Thursday 14:00-15:40 TB-4: COMEX - Applications to Economy
Room Pentagone 0A11 - Chair: W. Brauers

Thursday 14:00-15:40 TB-5: Networks
Room Pentagone 0A07 - Chair: B. Fortz

Thursday 16:10-17:25 TC-1: Mixed-integer nonlinear programming
Room Vesale 023 - Chair: Y. Crama

Thursday 16:10-17:25 TC-2: Decision Analysis 1
Room Vesale 020 - Chair: S. Eppe

Thursday 16:10-17:25 TC-3: Routing
Room Vesale 025 - Chair: K. Sörensen

Thursday 16:10-17:25 TC-4: Graphs
Room Pentagone 0A11 - Chair: H. Mélot
  • Number of non-equivalent colorings of a graph
    Hadrien Mélot (Université de Mons, Departement d'Informatique, Faculté des Sciences)
    Co-authors: A. Hertz
  • Price on symmetrisation and average distance
    Romain Absil (UMons)
  • Solving the Elementary Longest Path as a Mixed Integer Program
    Quoc Trung Bui (Université catholique de Louvain )
    Co-authors: Yves Deville, Pham Quang Dung
    Abstract:
    The Elementary Longest Path Problem (ELPP) consists of determining the longest path on a given graph such that every node appears at most once. The pro- blem arises in a variety of context, e.g., information retrieval, high-performance printed circuit board design, multi-robot patrolling. This problem is known to be NP-hard. In the literature, an exact algorithm for the ELPP is proposed in [7], where a Constraint Programming model is described together with intelligent search strategies to solve ELPP to optimality. One can easily show that, by adding some artificial nodes, the ELPP and the Elementary Shortest Path (between two specified nodes) Problem (ESPP) are equivalent. Two distinct mathematical for ESPP have been proposed in [2]. In this work, we propose a branch-and-cut algorithm based on the classi- cal formulation in [2]. First, we show a transformation from the ESPP to the Asymmetric Traveling Salesman Problem (ASTP) and vice versa. Then we adapt the valid inequalities of the ASTP (the Dk inequalities, Tk inequalities, and 2- matching inequalities) for the ESPP. Simple valid inequalities called maximum outflow inequalities for the ESPP are also proposed. We additionally develop- ped a simple and efficient algorithm for the separation of sub-tour elimination constraints. If many inequalities are generated in the separation step and are all added into the model, then the size of the model increases and the computation time for the linear relaxation may become costly. We therefore propose an in- equality filter to only keep the best constraints generated in the separation step. The filter is based on the idea of classes of inequalities and on violation threshold. In the experimental part of this work, we compare our branch-and-cut algo- rithm with two other existing algoritms, the Constraint Programming algorithm from [7], and the branch-and-cut algorithm from [2], but adapted to ESPP. The computational result shows that our branch-and-cut algorithm is faster than the one adapted from [2] and strongly outperforms the algorithm based on Constraint Programming.

Thursday 16:10-17:25 TC-5: Scheduling
Room Pentagone 0A07 - Chair: S. Hanafi

Friday 9:00-10:15 FA-1: Queuing
Room Vesale 023 - Chair: S. Wittevrongel

Friday 9:00-10:15 FA-2: Decision Analysis 2
Room Vesale 020 - Chair: R. Bisdorff

Friday 9:00-10:15 FA-3: COMEX - Optimization 2
Room Vesale 025 - Chair: M. Labbé

Friday 9:00-10:15 FA-4: Production
Room Pentagone 0A11 - Chair: D. Tuyttens

Friday 14:00-15:40 FB-1: Data Analysis 2
Room Vesale 023 - Chair: P. Fortemps

Friday 14:00-15:40 FB-2: Heuristics
Room Vesale 020 - Chair: T. Stützle

Friday 14:00-15:40 FB-3: COMEX - Transportation
Room Vesale 025 - Chair: F. Spieksma

Friday 14:00-15:40 FB-4: Health
Room Pentagone 0A11 - Chair: G. Vanden Berghe

 
 
  SOGESCI/ORBEL - Conference chair: Prof. M. Pirlot - Platform: Prof. M. Schyns