Graphical-structure-based models for routing problems

This paper presents an approach to the modelling of routing problems, focusing on the manner in which circuitous flow and conservation of flow are defined. The new modelling approach employs graphical constructs to define circuit requirements and allows a better description of real-world problems. Graphical constructs allow greater latitude than do existing modelling constructs, which can be inadequate and computationally inefficient. The flexibility and adaptability of graphical-structure-based models allows inclusion of balance constraints for typical routing problems. A hierarchical development, which makes use of the graphical structures employed in the model, is outlined for obtaining exact solutions.