Search Results for author: Andrea Lodi

Found 54 papers, 23 papers with code

One-for-many Counterfactual Explanations by Column Generation

no code implementations12 Feb 2024 Andrea Lodi, Jasone Ramírez-Ayerbe

In this paper, we consider the problem of generating a set of counterfactual explanations for a group of instances, with the one-for-many allocation rule, where one explanation is allocated to a subgroup of the instances.

counterfactual

Machine Learning Augmented Branch and Bound for Mixed Integer Linear Programming

no code implementations8 Feb 2024 Lara Scavuzzo, Karen Aardal, Andrea Lodi, Neil Yorke-Smith

We also address how to represent MILPs in the context of applying learning algorithms, MILP benchmarks and software.

A Reinforcement Learning Approach for Dynamic Rebalancing in Bike-Sharing System

no code implementations5 Feb 2024 Jiaqi Liang, Sanjay Dominik Jena, Defeng Liu, Andrea Lodi

Our work offers practical insights for operators and enriches the integration of reinforcement learning into dynamic rebalancing problems, paving the way for more intelligent and robust urban mobility solutions.

reinforcement-learning

Structured Pruning of Neural Networks for Constraints Learning

no code implementations14 Jul 2023 Matteo Cacciola, Antonio Frangioni, Andrea Lodi

In recent years, the integration of Machine Learning (ML) models with Operation Research (OR) tools has gained popularity across diverse applications, including cancer treatment, algorithmic configuration, and chemical process optimization.

Chemical Process

A machine learning framework for neighbor generation in metaheuristic search

no code implementations22 Dec 2022 Defeng Liu, Vincent Perreault, Alain Hertz, Andrea Lodi

Then, the key of the proposed methodology is to generate promising neighbors by selecting a proper subset of variables that contains a descent of the objective in the solution space.

Combinatorial Optimization Variable Selection

Learning to repeatedly solve routing problems

no code implementations15 Dec 2022 Mouad Morabit, Guy Desaulniers, Andrea Lodi

This partial prediction of the solution reduces the complexity of the problem and speeds up its resolution, while yielding a good quality solution.

Combinatorial Optimization

Connectivity-constrained Interactive Panoptic Segmentation

no code implementations13 Dec 2022 Ruobing Shen, Bo Tang, Andrea Lodi, Ismail Ben Ayed, Thomas Guthier

We address interactive panoptic annotation, where one segment all object and stuff regions in an image.

Panoptic Segmentation Segmentation

Learning to Compare Nodes in Branch and Bound with Graph Neural Networks

1 code implementation30 Oct 2022 Abdel Ghani Labassi, Didier Chételat, Andrea Lodi

Branch-and-bound approaches in integer programming require ordering portions of the space to explore next, a problem known as node comparison.

Neural Networks for Local Search and Crossover in Vehicle Routing: A Possible Overkill?

no code implementations9 Sep 2022 Ítalo Santana, Andrea Lodi, Thibaut Vidal

Extensive research has been conducted, over recent years, on various ways of enhancing heuristic search for combinatorial optimization problems with machine learning algorithms.

Combinatorial Optimization

Implementing a Hierarchical Deep Learning Approach for Simulating Multi-Level Auction Data

1 code implementation25 Jul 2022 Igor Sadoune, Andrea Lodi, Marcelin Joanis

We present a deep learning solution to address the challenges of simulating realistic synthetic first-price sealed-bid auction data.

Density Estimation

Lookback for Learning to Branch

no code implementations30 Jun 2022 Prateek Gupta, Elias B. Khalil, Didier Chetélat, Maxime Gasse, Yoshua Bengio, Andrea Lodi, M. Pawan Kumar

Given that B&B results in a tree of sub-MILPs, we ask (a) whether there are strong dependencies exhibited by the target heuristic among the neighboring nodes of the B&B tree, and (b) if so, whether we can incorporate them in our training procedure.

Model Selection Variable Selection

Deep Neural Networks pruning via the Structured Perspective Regularization

no code implementations28 Jun 2022 Matteo Cacciola, Antonio Frangioni, Xinlin Li, Andrea Lodi

In Machine Learning, Artificial Neural Networks (ANNs) are a very powerful tool, broadly used in many applications.

A Stochastic Proximal Method for Nonsmooth Regularized Finite Sum Optimization

1 code implementation14 Jun 2022 Dounia Lakhmiri, Dominique Orban, Andrea Lodi

We consider the problem of training a deep neural network with nonsmooth regularization to retrieve a sparse and efficient sub-structure.

MIP-GNN: A Data-Driven Framework for Guiding Combinatorial Solvers

1 code implementation27 May 2022 Elias B. Khalil, Christopher Morris, Andrea Lodi

Mixed-integer programming (MIP) technology offers a generic way of formulating and solving combinatorial optimization problems.

Combinatorial Optimization

Learning to branch with Tree MDPs

1 code implementation23 May 2022 Lara Scavuzzo, Feng Yang Chen, Didier Chételat, Maxime Gasse, Andrea Lodi, Neil Yorke-Smith, Karen Aardal

State-of-the-art Mixed Integer Linear Program (MILP) solvers combine systematic tree search with a plethora of hard-coded heuristics, such as the branching rule.

Reinforcement Learning (RL)

Fast Continuous and Integer L-shaped Heuristics Through Supervised Learning

no code implementations2 May 2022 Eric Larsen, Emma Frejinger, Bernard Gendron, Andrea Lodi

Our extensive empirical analysis is grounded in standardized families of problems derived from stochastic server location (SSLP) and stochastic multi knapsack (SMKP) problems available in the literature.

Management

Revisiting local branching with a machine learning lens

1 code implementation3 Dec 2021 Defeng Liu, Matteo Fischetti, Andrea Lodi

In this work, we study the relation between the size of the search neighborhood and the behavior of the underlying LB algorithm, and we devise a leaning based framework for predicting the best size for the specific instance to be solved.

BIG-bench Machine Learning

Adaptive First- and Second-Order Algorithms for Large-Scale Machine Learning

no code implementations29 Nov 2021 Sanae Lotfi, Tiphaine Bonniot de Ruisselet, Dominique Orban, Andrea Lodi

In this paper, we consider both first- and second-order techniques to address continuous optimization problems arising in machine learning.

BIG-bench Machine Learning Stochastic Optimization

Guidelines for the Computational Testing of Machine Learning approaches to Vehicle Routing Problems

no code implementations28 Sep 2021 Luca Accorsi, Andrea Lodi, Daniele Vigo

Despite the extensive research efforts and the remarkable results obtained on Vehicle Routing Problems (VRP) by using algorithms proposed by the Machine Learning community that are partially or entirely based on data-driven analysis, most of these approaches are still seldom employed by the Operations Research (OR) community.

BIG-bench Machine Learning

On the estimation of discrete choice models to capture irrational customer behaviors

no code implementations8 Sep 2021 Sanjay Dominik Jena, Andrea Lodi, Claudio Sole

Specifically, we show how to use partially-ranked preferences to efficiently model rational and irrational customer types from transaction data.

Discrete Choice Models

Learning to Schedule Heuristics in Branch and Bound

1 code implementation NeurIPS 2021 Antonia Chmiela, Elias Boutros Khalil, Ambros Gleixner, Andrea Lodi, Sebastian Pokutta

Compared to the default settings of a state-of-the-art academic MIP solver, we are able to reduce the average primal integral by up to 49% on two classes of challenging instances.

Decision Making Scheduling

Ecole: A Library for Learning Inside MILP Solvers

1 code implementation6 Apr 2021 Antoine Prouvost, Justin Dumouchelle, Maxime Gasse, Didier Chételat, Andrea Lodi

In this paper we describe Ecole (Extensible Combinatorial Optimization Learning Environments), a library to facilitate integration of machine learning in combinatorial optimization solvers.

BIG-bench Machine Learning Combinatorial Optimization +1

Predicting the probability distribution of bus travel time to move towards reliable planning of public transport services

no code implementations3 Feb 2021 Léa Ricard, Guy Desaulniers, Andrea Lodi, Louis-Martin Rousseau

Two types of probabilistic models, namely similarity-based density estimation models and a smoothed Logistic Regression for probabilistic classification model, are compared on a dataset of more than 41, 000 trips and 50 bus routes of the city of Montr\'eal.

Density Estimation Scheduling

Reinforcement Learning for Freight Booking Control Problems

no code implementations29 Jan 2021 Justin Dumouchelle, Emma Frejinger, Andrea Lodi

Routinely solving such operational problems when deploying reinforcement learning algorithms may be too time consuming.

BIG-bench Machine Learning Decision Making +3

Assessing the Impact: Does an Improvement to a Revenue Management System Lead to an Improved Revenue?

no code implementations13 Jan 2021 Greta Laage, Emma Frejinger, Andrea Lodi, Guillaume Rabusseau

This is a challenging problem as it corresponds to the difference between the generated value and the value that would have been generated keeping the system as before.

counterfactual Management

Stochastic Damped L-BFGS with Controlled Norm of the Hessian Approximation

no code implementations10 Dec 2020 Sanae Lotfi, Tiphaine Bonniot de Ruisselet, Dominique Orban, Andrea Lodi

We propose a new stochastic variance-reduced damped L-BFGS algorithm, where we leverage estimates of bounds on the largest and smallest eigenvalues of the Hessian approximation to balance its quality and conditioning.

regression

Change Point Detection by Cross-Entropy Maximization

no code implementations2 Sep 2020 Aurélien Serre, Didier Chételat, Andrea Lodi

Many offline unsupervised change point detection algorithms rely on minimizing a penalized sum of segment-wise costs.

Change Point Detection

Hybrid Models for Learning to Branch

1 code implementation NeurIPS 2020 Prateek Gupta, Maxime Gasse, Elias B. Khalil, M. Pawan Kumar, Andrea Lodi, Yoshua Bengio

First, in a more realistic setting where only a CPU is available, is the GNN model still competitive?

The Covering-Assignment Problem for Swarm-powered Ad-hoc Clouds: A Distributed 3D Mapping Use-case

1 code implementation21 Apr 2020 Leandro R. Costa, Daniel Aloise, Luca G. Gianoli, Andrea Lodi

Besides automating field operations, a drone swarm can serve as an ad-hoc cloud infrastructure built on top of computing and storage resources available across the swarm members and other connected elements.

3D Reconstruction

Parameterizing Branch-and-Bound Search Trees to Learn Branching Policies

1 code implementation12 Feb 2020 Giulia Zarpellon, Jason Jo, Andrea Lodi, Yoshua Bengio

We aim instead at learning a policy that generalizes across heterogeneous MILPs: our main hypothesis is that parameterizing the state of the B&B search tree can aid this type of generalization.

Imitation Learning

A learning-based algorithm to quickly compute good primal solutions for Stochastic Integer Programs

1 code implementation17 Dec 2019 Yoshua Bengio, Emma Frejinger, Andrea Lodi, Rahul Patel, Sriram Sankaranarayanan

We propose a novel approach using supervised learning to obtain near-optimal primal solutions for two-stage stochastic integer programming (2SIP) problems with constraints in the first and second stages.

Game theoretical analysis of Kidney Exchange Programs

1 code implementation20 Nov 2019 Margarida Carvalho, Andrea Lodi

Recently, this was formulated as a non-cooperative two-player game and the game solutions (equilibria) were characterized when the entities objective function is the number of their patients receiving a kidney.

Computer Science and Game Theory 91-XX, 05Cxx, 90-XX

Learning chordal extensions

no code implementations16 Oct 2019 Defeng Liu, Andrea Lodi, Mathieu Tanneau

As a first building block of the learning framework, we propose an on-policy imitation learning scheme that mimics the elimination ordering provided by the (classical) minimum degree rule.

Combinatorial Optimization Imitation Learning

When Nash Meets Stackelberg

1 code implementation14 Oct 2019 Margarida Carvalho, Gabriele Dragotto, Felipe Feijoo, Andrea Lodi, Sriram Sankaranarayanan

This article introduces a class of $Nash$ games among $Stackelberg$ players ($NASPs$), namely, a class of simultaneous non-cooperative games where the players solve sequential Stackelberg games.

Computer Science and Game Theory Optimization and Control

Connectivity-constrained interactive annotations for panoptic segmentation

no code implementations25 Sep 2019 Ruobing Shen, Bo Tang, Ismail Ben Ayed, Andrea Lodi, Thomas Guthier

Large-scale ground truth data sets are of crucial importance for deep learning based segmentation models, but annotating per-pixel masks is prohibitively time consuming.

Panoptic Segmentation Segmentation +1

Learning to Handle Parameter Perturbations in Combinatorial Optimization: an Application to Facility Location

no code implementations12 Jul 2019 Andrea Lodi, Luca Mossina, Emmanuel Rachelson

Although presented through the application to the facility location problem, the approach developed here is general and explores a new perspective on the exploitation of past experience in combinatorial optimization.

Combinatorial Optimization

Activation Adaptation in Neural Networks

no code implementations28 Jan 2019 Farnoush Farhadi, Vahid Partovi Nia, Andrea Lodi

Given the activation function, the neural network is trained over the bias and the weight parameters.

Predicting Tactical Solutions to Operational Planning Problems under Imperfect Information

no code implementations22 Jan 2019 Eric Larsen, Sébastien Lachapelle, Yoshua Bengio, Emma Frejinger, Simon Lacoste-Julien, Andrea Lodi

We formulate the problem as a two-stage optimal prediction stochastic program whose solution we predict with a supervised machine learning algorithm.

BIG-bench Machine Learning Management

Machine Learning for Combinatorial Optimization: a Methodological Tour d'Horizon

no code implementations15 Nov 2018 Yoshua Bengio, Andrea Lodi, Antoine Prouvost

This paper surveys the recent attempts, both from the machine learning and operations research communities, at leveraging machine learning to solve combinatorial optimization problems.

BIG-bench Machine Learning Combinatorial Optimization

Learning to rank for censored survival data

1 code implementation6 Jun 2018 Margaux Luck, Tristan Sylvain, Joseph Paul Cohen, Heloise Cardinal, Andrea Lodi, Yoshua Bengio

Survival analysis is a type of semi-supervised ranking task where the target output (the survival time) is often right-censored.

Learning-To-Rank Survival Analysis

An ILP Solver for Multi-label MRFs with Connectivity Constraints

no code implementations16 Dec 2017 Ruobing Shen, Eric Kendinibilir, Ismail Ben Ayed, Andrea Lodi, Andrea Tramontani, Gerhard Reinelt

The method enforces connectivity priors iteratively by a cutting plane method, and provides feasible solutions with a guarantee on sub-optimality even if we terminate it earlier.

Weakly supervised segmentation

Deep Learning for Patient-Specific Kidney Graft Survival Analysis

2 code implementations29 May 2017 Margaux Luck, Tristan Sylvain, Héloïse Cardinal, Andrea Lodi, Yoshua Bengio

An accurate model of patient-specific kidney graft survival distributions can help to improve shared-decision making in the treatment and care of patients.

Decision Making Multi-Task Learning +1

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