An improved graph attention network combined with reinforcement learning for capacitated vehicle routing problem
摘要
The capacitated vehicle routing problem (CVRP), as a core combinatorial optimization (CO) problem in modern logistics distribution systems, holds significant research value. In this work, a novel encoder-decoder framework called residual edge demand graph attention network encoder and multiple attention-based decoders (REDGAT-MA) is presented to address CVRP, trained end-to-end via REINFORCE algorithm with a high-quality baseline. On one hand, the encoder extracts and reconstructs node features and interconnections through a residual graph attention network, which produces powerful node representations by integrating node features, edge features, and node demands. And new feature embedding vectors for the decoder are generated at the same time. On the other hand, the attention-based decoders dynamically decode routing sequences by integrating real-time operational constraints–including residual vehicle capacity and customer demand on the basis of the new feature embedding vectors. Then the multiple decoders mechanism constructs multiple feasible solutions for each iteration for a single instance. REDGAT-MA narrows the gap to solver with 1.64%, 1.83%, and 3.33% for three different scales of random CVRP instances, and achieves average gaps of 3.49%, 3.80%, and 8.27% for the problems with same scales from CVRPLIB, which demonstrates the model’s efficiency and generalization capabilities. Furthermore, the results from real-world distribution tasks conducted by JD logistics (JDL) in Beijing further validate the algorithm’s effectiveness.