đ€ AI Summary
Industrial symbiosis is constrained by socio-spatial frictionsâincluding transportation costs and inefficient resource matchingâyet existing models neglect the coupled effects of spatial structure, market mechanisms, and firmsâ adaptive behaviors. To address this, we develop a spatially embedded double-auction multi-agent model integrating topological networks, deep Q-networks (DQN) and proximal policy optimization (PPO) reinforcement learning, and counterfactual regret minimization. The model simulates heterogeneous firmsâ decentralized, locally driven decisions on by-product exchange. We demonstrate for the first time how stable, near-Nash equilibrium circulation patterns spontaneously emerge under resource scarcity and spatial constraints through decentralized coordination. Furthermore, we identify critical combinations of spatial density and market parameters that drive high circulation rates. Our findings provide quantifiable theoretical foundations and simulation-based evidence to inform incentive-compatible, sustainable industrial policy design.
đ Abstract
Industrial symbiosis fosters circularity by enabling firms to repurpose residual resources, yet its emergence is constrained by socio-spatial frictions that shape costs, matching opportunities, and market efficiency. Existing models often overlook the interaction between spatial structure, market design, and adaptive firm behavior, limiting our understanding of where and how symbiosis arises. We develop an agent-based model where heterogeneous firms trade byproducts through a spatially embedded double-auction market, with prices and quantities emerging endogenously from local interactions. Leveraging reinforcement learning, firms adapt their bidding strategies to maximize profit while accounting for transport costs, disposal penalties, and resource scarcity. Simulation experiments reveal the economic and spatial conditions under which decentralized exchanges converge toward stable and efficient outcomes. Counterfactual regret analysis shows that sellers' strategies approach a near Nash equilibrium, while sensitivity analysis highlights how spatial structures and market parameters jointly govern circularity. Our model provides a basis for exploring policy interventions that seek to align firm incentives with sustainability goals, and more broadly demonstrates how decentralized coordination can emerge from adaptive agents in spatially constrained markets.