Demonstration of Duality of Fractal Gravity Models by Scaling Symmetry

TL;DR

This paper proves the duality of fractal gravity models using scaling invariance, supported by empirical data from China's Beijing-Tianjin-Hebei region, enhancing understanding of spatial interaction modeling.

Contribution

It provides a theoretical proof of the duality in fractal gravity models based on scaling symmetry, bridging empirical observations with mathematical foundations.

Findings

Duality of fractal gravity models is rooted in scaling symmetry.

Empirical data supports the theoretical derivation.

The work advances understanding of spatial interaction modeling.

Abstract

A pair of fractal gravity models can be derived from the spatial interaction models based on entropy maximizing principle and allometric scaling law. The models can be expressed as dual form in mathematics and are important for analyzing and predicting spatial flows in network of cities. However, the dual relationship of urban gravity parameters has been an empirical relationship for a long time and lacks theoretical proof. This paper is devoted to proving the duality of fractal gravity models by means of ideas from scaling invariance. The results show that a fractal gravity model can be derived from its dual form. The observational data of interurban spatial flows of Beijing-Tianjin-Hebei region of China are employed to make a case study, lending a further support to the theoretical derivation. A conclusion can be reached that the duality of gravity models rests with scaling symmetry of fractal structure. This work may be helpful for understanding the theoretical essence and application direction of spatial interaction modeling.