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1499. Automatic model decomposition in Hexaly Optimizer
Invited abstract in session WA-30: Optimization Tools, stream Software for Optimization.
Wednesday, 8:30-10:00Room: 064 (building: 208)
Authors (first author is the speaker)
| 1. | Julien Darlay
|
| Hexaly |
Abstract
Hexaly Optimizer, formerly known as LocalSolver, is a model and run solver that integrates heuristics and exact methods. A set-based modeling formalism was introduced to simplify the modeling of certain combinatorial problems like routing or packing problems. For instance, in a routing problem, list variables can be used to model the sequence of visits made by each truck. These decision variables are well suited for a heuristic search but are much more difficult to integrate in a mathematical programming approach to compute lower bounds. A direct reformulation in a MILP model introduces a quadratic number of binary decisions with several big M constraints leading to poor scalability and bounds. Hexaly 13.0 automatically detects such structures in a user model and reformulates them in an extended MILP model to compute lower bounds. This model is solved efficiently using state of the art branch-cut-and-price technics from the literature. This talk will present the general approach and the algorithms used for the resolution and some benchmarks on the CVRP library.
Keywords
- Mathematical Programming
- Software
- Column Generation
Status: accepted
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