Cross-Problem Learning for Solving Vehicle Routing Problems
This addresses the problem of computational redundancy for researchers and practitioners in optimization by enabling transferable knowledge across VRP variants, though it is incremental as it builds on existing neural heuristics and fine-tuning techniques.
The paper tackles the inefficiency of training neural heuristics separately for each vehicle routing problem (VRP) variant by proposing cross-problem learning, which pre-trains a Transformer backbone on the traveling salesman problem and fine-tunes it for other VRPs, achieving significantly better performance and parameter efficiency compared to training from scratch.
Existing neural heuristics often train a deep architecture from scratch for each specific vehicle routing problem (VRP), ignoring the transferable knowledge across different VRP variants. This paper proposes the cross-problem learning to assist heuristics training for different downstream VRP variants. Particularly, we modularize neural architectures for complex VRPs into 1) the backbone Transformer for tackling the travelling salesman problem (TSP), and 2) the additional lightweight modules for processing problem-specific features in complex VRPs. Accordingly, we propose to pre-train the backbone Transformer for TSP, and then apply it in the process of fine-tuning the Transformer models for each target VRP variant. On the one hand, we fully fine-tune the trained backbone Transformer and problem-specific modules simultaneously. On the other hand, we only fine-tune small adapter networks along with the modules, keeping the backbone Transformer still. Extensive experiments on typical VRPs substantiate that 1) the full fine-tuning achieves significantly better performance than the one trained from scratch, and 2) the adapter-based fine-tuning also delivers comparable performance while being notably parameter-efficient. Furthermore, we empirically demonstrate the favorable effect of our method in terms of cross-distribution application and versatility.