We propose a decentralized market model in which agents can negotiate bilateral contracts. This builds on a similar, but centralized, model of trading networks introduced by Hatfield et al. (2013). Prior work has established that fully-substitutable preferences guarantee the existence of competitive equilibria which can be centrally computed. Our motivation comes from the fact that prices in markets such as over-the-counter markets and used car markets arise from \textit{decentralized} negotiation among agents, which has left open an important question as to whether equilibrium prices can emerge from agent-to-agent bilateral negotiations. We design a best response dynamic intended to capture such negotiations between market participants. We assume fully substitutable preferences for market participants. In this setting, we provide proofs of convergence for sparse markets ({covering many real world markets of interest}), and experimental results for more general cases, demonstrating that prices indeed reach equilibrium, quickly, via bilateral negotiations. Our best response dynamic, and its convergence behavior, forms an important first step in understanding how decentralized markets reach, and retain, equilibrium.

翻译：本文提出了一种去中心化市场模型，其中各参与主体可通过双边协商达成合约。该模型建立在Hatfield等人（2013）提出的集中式交易网络模型基础之上。已有研究表明，在完全可替代偏好条件下，竞争均衡的存在性可被证明，且可通过集中计算获得。本研究的动机源于现实市场中（如场外交易市场和二手车市场）价格形成于参与主体间的去中心化协商过程，这引出了一个重要问题：均衡价格能否通过主体间的双边协商自然涌现？为此，我们设计了一种用于刻画市场参与者间协商过程的最优响应动态机制。在假设市场参与者具有完全可替代偏好的前提下，我们针对稀疏市场（涵盖众多实际市场形态）给出了收敛性证明，并对更一般情形进行了实验验证。结果表明，通过双边协商，价格确实能够快速收敛至均衡状态。本研究提出的最优响应动态及其收敛特性，为理解去中心化市场如何实现并维持均衡迈出了重要的第一步。