Abstract: Sustainable public procurement (SPP) refers to the requirement for government procurement activities to achieve the fundamental economic function of “value for money” while fully leveraging the sustainable policy function of guiding environmental protection and fulfilling social responsibilities. With the increasing scale of SPP, covert operations in the supply of sustainable products become more frequent. Issues such as the inadequacy of sustainable labeling systems, the absence of product standards, and the falsification of product certificates become more pronounced. The problem with “sustainable corruption” wherein procurement personnel and suppliers collude, shield each other, and conspire for rent-seeking, continues to hinder the rational operation of the public sector procurement chain.
   Existing research has explored the causes, harms, and necessity of regulatory measures in rent-seeking corruption within SPP. However, there is a scarcity of research at the mathematical level examining the mechanisms of rent-seeking and regulation, with a notable gap in the study of decision-making behavior in SPP. In light of this, this paper aims to analyze the dynamic evolution mechanisms of rent-seeking and regulatory behavior among regulatory authorities, procurement personnel, and suppliers in SPP. By constructing an asymmetric tripartite dynamic evolutionary game model, the paper discusses the evolutionary strategies and conditions of rent-seeking and regulation generated by various stakeholders in the purchase of sustainable products. The stability of equilibrium points is verified using a system dynamics model. To obtain the optimal solution for the model and optimize its stability, a dynamic reward-penalty mechanism is introduced to enhance the model, ultimately yielding the optimal evolutionary stable strategy.
   The research results indicate that, on the one hand, government regulatory costs, procurement personnel psychological expectations, rent-seeking profit space, and reward-penalty thresholds are critical factors influencing the evolution of the tripartite game. Reducing regulatory costs, raising psychological expectations of procurement personnel, and expanding the bidding scope contribute to lowering rent-seeking risks. On the other hand, by introducing a reward-penalty mechanism to stabilize the model, considering both rent-seeking probability and corruption level in the dynamic mechanism, the strategy combination of “government not to regulate, procurement personnel not to rent-seek, and suppliers to provide sustainable products” is the ultimately obtained evolutionary stable strategy, confirming the results deduced from the initial model.
   The research findings can provide the theoretical basis for optimizing the procurement decisions, procedures, and regulatory mechanisms of SPP sectors. Based on the analysis and conclusions above, this paper suggests establishing a tripartite network autonomy model involving regulatory authorities, procurement personnel, and suppliers for sustainable procurement in government. Before the formation of this mode, firstly, it is necessary to improve the reward and punishment mechanism to guide self-restraint and incentives for both buyers and suppliers. Secondly, there is a need to strengthen the education on integrity and professionalism of procurement personnel and improve government procurement regulatory systems. Thirdly, it is essential to broaden the scope of tendering and eliminate single-source bidding for non-specific products, thereby reducing the rent-seeking space for a few individual suppliers and lowering the possibility of collusion between both parties for rent-seeking.

Key words: sustainable public procurement, rent-seeking and supervision, evolutionary game, reward-punishment mechanism

摘要： 可持续公共采购的腐败风险在近年来受到学术界的高度关注,本文旨在借助演化博弈和系统动力学探究可持续公共采购中三方主体(政府监管部门、采购人员和供应商)寻租与监管的动态演化博弈过程,并引入动态奖励-惩罚机制对模型进行改进,以寻求稳定控制的最优演化策略。研究结果表明:①政府监管成本、采购人员心理期望、寻租收益空间以及奖惩额度是影响三方演化博弈的关键因素。降低监管成本,提高采购人员心理预期,扩大招标范围有助于降低寻租风险。②通过引入奖励-惩罚机制对模型进行稳定性控制,在同时考虑寻租概率和腐败程度的动态机制下,“政府不监管、采购人员不寻租和供应商提供可持续产品”的策略组合是最终得到的演化稳定策略,这一结论与初始模型推导的结果相印证。以该策略为基础,进而对可持续公共采购部门的采购决策、程序和监管机制的优化提出政策建议。

关键词: 可持续公共采购, 寻租监管, 演化博弈, 奖励-惩罚机制