A Machine Learning Approach to Two-Stage Adaptive Robust Optimization
This provides a faster method for solving optimization problems in domains like facility location and inventory control, though it appears incremental as it builds on existing algorithms.
The authors tackled two-stage adaptive robust optimization problems with binary variables by training a machine learning model to predict optimal strategies from pre-solved instances, achieving drastically faster solution times with high accuracy compared to state-of-the-art algorithms.
We propose an approach based on machine learning to solve two-stage linear adaptive robust optimization (ARO) problems with binary here-and-now variables and polyhedral uncertainty sets. We encode the optimal here-and-now decisions, the worst-case scenarios associated with the optimal here-and-now decisions, and the optimal wait-and-see decisions into what we denote as the strategy. We solve multiple similar ARO instances in advance using the column and constraint generation algorithm and extract the optimal strategies to generate a training set. We train a machine learning model that predicts high-quality strategies for the here-and-now decisions, the worst-case scenarios associated with the optimal here-and-now decisions, and the wait-and-see decisions. We also introduce an algorithm to reduce the number of different target classes the machine learning algorithm needs to be trained on. We apply the proposed approach to the facility location, the multi-item inventory control and the unit commitment problems. Our approach solves ARO problems drastically faster than the state-of-the-art algorithms with high accuracy.