Food Security under Trade Policies and Perishability: Extensions of the Multicommodity Network Equilibrium Model with Monotonicity Analysis

Building on recent work about multicommodity agricultural trade and food security, this paper develops a network equilibrium model with nutritional constraints formulated as a variational inequality problem. A key contribution of the paper is its monotonicity analysis of the associated operator. We establish sufficient conditions for strong monotonicity under general and separable affine price and transportation cost functions, thereby providing existence and uniqueness guarantees for equilibrium solutions. The framework is further extended to incorporate ad valorem tariffs and commodity perishability, allowing the analysis of more realistic international trade settings. Numerical experiments based on global wheat trade data illustrate the effects of nutritional requirements, trade policies, and perishability on equilibrium trade patterns and food security outcomes.