Senior Optimization Scientist
About Nicolas
Articles written by Nicolas
Hexaly vs Google OR-Tools on the Pickup and Delivery Problem with Time Windows (PDPTW) April 10, 2023
In the Pickup and Delivery Problem with Time Windows (PDPTW), vehicles must collect and deliver items according to customers’ demands. It must do so during opening hours. The vehicles start and end their routes at a depot. Each customer must be served by one and only one vehicle. The goal is to assign a sequence…
Hexaly on huge instances of the Capacitated Vehicle Routing Problem (CVRP) October 31, 2022
The 12th DIMACS Implementation Challenge, a renowned mathematical optimization competition, focused on solving Vehicle Routing Problems (VRP). The goal of such an event, bringing together the best experts and researchers in the field, is to have a clear picture of the state of the art on a given class of problems, like VRP, by practically…
Hexaly vs Gurobi on the Capacitated Vehicle Routing Problem with Time Windows (CVRPTW) October 24, 2022
In the Capacitated Vehicle Routing Problem with Time Windows (CVRPTW), a fleet of delivery vehicles with uniform capacity must serve customers with known demand for a single commodity. The vehicles start and end their routes at a joint depot. Each customer can only be served by one vehicle and must be visited within its time window.…
Hexaly vs Gurobi on the Capacitated Vehicle Routing Problem (CVRP) October 17, 2022
In the Capacitated Vehicle Routing Problem (CVRP), a fleet of delivery vehicles with uniform capacity must service customers with known demand for a single commodity. The vehicles start and end their routes at a common depot. Each customer can only be served by one vehicle. Given a fleet of vehicles, the objective is to assign…
Broken records for the Movie Shoot Scheduling Problem February 7, 2022
In this post, we describe and analyze the LocalSolver model of a simplified version of the Movie Shoot Scheduling Problem defined by Bomsdorf and Derigs in an OR Spectrum paper. This version is the subject of online competition on the Optimization Hub. A movie consists of a set of scenes. Each scene must be shot in a given location…
Hexaly vs Gurobi on the Traveling Salesman Problem (TSP) July 26, 2021
The Traveling Salesman Problem (TSP) is defined as follows: given a set of cities and distances for all pairs of cities, find a roundtrip of minimal total length visiting each city exactly once. Hexaly Optimizer reaches an average optimality gap of 0.25% in 60 seconds of running time on Traveling Salesman Problem instances with up to 2,000…
Hexaly vs Gurobi on the K-Means Clustering Problem (MSSC) May 24, 2021
The K-Means Clustering problem is defined as follows: given a set of points along some dimensions, find a partition of these points into k clusters. The total sum of squared Euclidean distances between each cluster’s centroid and its elements is minimized. This problem is also known as the Minimum Sum-of-Squares Clustering (MSSC). Hexaly Optimizer reaches gaps below…