Ecole

Ecole (pronounced [ekɔl]) stands for Extensible Combinatorial Optimization Learning Environments and aims to expose a number of control problems arising in combinatorial optimization solvers as Markov Decision Processes (i.e., Reinforcement Learning environments). Rather than trying to predict solutions to combinatorial optimization problems directly, the philosophy behind Ecole is to work in cooperation with a state-of-the-art Mixed Integer Linear Programming solver that acts as a controllable algorithm.

The underlying solver used is SCIP, and the user facing API is meant to mimic the OpenAI Gym API (as much as possible).

import ecole

env = ecole.environment.Branching(
    reward_function=-1.5 * ecole.reward.LpIterations() ** 2,
    observation_function=ecole.observation.NodeBipartite(),
)
instances = ecole.instance.SetCoverGenerator()

for _ in range(10):
    obs, action_set, reward_offset, done, info = env.reset(next(instances))
    while not done:
        obs, action_set, reward, done, info = env.step(action_set[0])

Installation

Conda

conda install -c conda-forge ecole

All dependencies are resolved by conda, no compiler is required.

Pip wheel (binary)

Currently unavailable.

Pip source

Building from source requires:

• A C++17 compiler,

• A SCIP installation.

pip install ecole

Other Options

Checkout the installation instructions in the documentation for more installation options.

Use It, Cite It

If you use Ecole in a scientific publication, please cite the Ecole publication

@inproceedings{
    prouvost2020ecole,
    title={Ecole: A Gym-like Library for Machine Learning in Combinatorial Optimization Solvers},
    author={Antoine Prouvost and Justin Dumouchelle and Lara Scavuzzo and Maxime Gasse and Didier Ch{\'e}telat and Andrea Lodi},
    booktitle={Learning Meets Combinatorial Algorithms at NeurIPS2020},
    year={2020},
    url={https://openreview.net/forum?id=IVc9hqgibyB}
}