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今天小编为大家带来《区块链技术对供应链金融的影响
———基于三方博弈、动态演化博弈的视角》一文。
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Today, the editor brings the "
The impact of blockchain technology on supply chain finance-- Based on the perspective of three-party game and dynamic evolutionary game".
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1 内容摘要（Content summary）
今天小编将从“思维导图、精读内容、知识补充”三个板块，解读分享《区块链技术对供应链金融的影响—基于三方博弈、动态演化博弈的视角》一文的第三章中银行期望收益函数部分。
Today, I will read and share the part of bank's expected return function in the third chapter of the article "The Impact of Blockchain Technology on Supply Chain Finance-Based on the Perspective of Three-Party Game and Dynamic Evolutionary Game" from the three sections of "Thinking Guide, Intensive Reading and Knowledge Supplementation".
2 思维导图（Mind mapping）
3 精读内容（Intensive reading content）
3.1前提假设（Premise）
区块链技术可筛选高质量应收账款/票据，通过物联网模块能够清晰的识别基础资产存续的真实性和合法性，将筛选出应收账款／票据的质量相对较高的项目，当融资企业不还款时，银行通过对应收账款／商业票据的变现价值提高，即提高δ（折扣率）。
Blockchain technology can screen high-quality accounts receivable/notes, through the IoT module can clearly identify the authenticity and legitimacy of the underlying assets survival, will screen out the accounts receivable/notes of relatively high quality of the project, when the financing enterprise does not pay back, the bank through the accounts receivable/commercial paper of the realization of the value of the increase, that is, to increase the δ (discount rate).
该文利用非对称演化博弈模型进一步探究区块链技术对供应链金融的影响。银行是否愿意*款贷**还取决于对供应链系统稳定水平的判断。实践中银行对供应链稳定程度了解有限，存在信息不对称，银行出于谨慎性的考虑往往会低估 Ｐ＋Ｓ的值，银行有不放贷的倾向。
The paper further explores the impact of blockchain technology on supply chain finance using an asymmetric evolutionary game model. The bank's willingness to lend also depends on the judgment of the stability level of the supply chain system. In practice, banks have limited understanding of the stability level of the supply chain, there is information asymmetry, banks tend to underestimate the value of P + S out of prudence, and banks have a tendency not to lend.
区块链无法约束供应链上下游企业之间的稳定性，即 Ｐ＋Ｓ的值的大小不受区块链联盟的约束，故可以假设简化模型，此时融资企业、核心企业利益一致，故将供应链上下游融资企业、核心企业视为一个博弈方，为供应链系统。
Blockchain can not constrain the stability between the upstream and downstream enterprises in the supply chain, that is, the size of the value of P + S is not subject to the constraints of the blockchain alliance, so it can be assumed that the simplified model, at this time, the financing enterprise, the core enterprise interests are the same, therefore, the supply chain upstream and downstream financing enterprises, the core enterprise is regarded as a game party for the supply chain system.
假设供应链金融市场上有大量的银行和供应链系统进行博弈，基于三方博弈的均衡结果，构建两方演化博弈模型，其中，供应链系统融资效率为：
Ｒｔ ＝ｒαＬ －αｉＬ ＋Ｓ－Ｎ －Ｆ／２
Assuming that there are a large number of banks and supply chain systems in the supply chain finance market to play the game, based on the equilibrium results of the three-party game, the two-party evolutionary game model is constructed, in which the financing efficiency of the supply chain system is:
Ｒｔ ＝ｒαＬ －αｉＬ ＋Ｓ－Ｎ －Ｆ／２
3.2构建两方动态演化博弈支付矩阵（Constructing a two-party dynamic evolutionary game payment matrix）
假设区块链技术的引入和维护成本为 Ｆ，由供应链系统和银行均摊，在区块链＋供应链金融中事前交易成本大幅降低，本文假设Ｃｂ 为０，同时 Ｎ 值较大。ｐ表示的银行利用区块链＋供应链金融*款贷**占所有银行的比例，则１－ｐ 为非区块链－供应链金融模式的银行比例。ｑ为供应链系统选择还款的比例，１－ｑ为供应链系统违约的比例。
Assuming that the introduction and maintenance cost of blockchain technology is F, which is shared equally by the supply chain system and the banks, the ex ante transaction cost is reduced significantly in blockchain + supply chain finance, and this paper assumes that Cb is 0, while the value of N is large. p denotes the proportion of banks utilizing blockchain + supply chain finance loans to all banks, and 1-p is the proportion of banks with a non-blockchain -supply chain finance model of banks. q is the proportion of supply chain system choosing to repay, and 1-q is the proportion of supply chain system default.
3.3构建和讨论银行期望利润函数（Construct and discuss the bank's expected profit function）
根据两方动态演化博弈支付矩阵，计算银行期望利润函数如下：
Based on the two-party dynamic evolutionary game payment matrix, the bank's expected profit function is calculated as follows:
讨论δＬ－αＬ－αｉＬ与0比较的大小关系。当其小于0时，计算复制动态方程及其导数。令其复制动态方程为0求出相应取值。对每个取值进行相应讨论，得出各情形下的演化稳定策略，计算和讨论过程如下：
Discuss the magnitude of δL-αL-αiL compared to 0. Calculate the replicated dynamic equation and its derivatives when it is less than 0. Let its replicated dynamic equation be 0 to find the corresponding values. Discuss each value accordingly to derive the evolutionary stabilization strategy for each scenario, the calculation and discussion process is as follows:
4 知识补充（Knowledge supplement）
什么是演化博弈？（What is an evolutionary game?）
在博弈论中，演化博弈是一种研究策略演变和群体动态的模型。它通常涉及到在群体中的多个个体之间进行博弈，这些个体的策略会根据其成功的程度而被选择和传递给下一代。
In game theory, an evolutionary game is a model for studying strategy evolution and group dynamics. It usually involves playing a game between multiple individuals in a group whose strategies are selected and passed on to the next generation based on their level of success.
以下是演化博弈的一般步骤：
The following are the general steps of an evolutionary game:
1.定义策略和利益：首先，需要明确定义个体可能采取的不同策略，以及这些策略在某种环境下的利益或收益。这可以包括个体之间的合作与竞争，或者不同的决策选择。
1.Define strategies and benefits: first, there is a need to explicitly define the different strategies that individuals may adopt and the benefits or gains of these strategies in a given context. This can include cooperation and competition between individuals, or different decision options.
2.确定支付矩阵：对于每一对个体之间的互动，构建一个支付矩阵，其中包含了每个个体在不同策略组合下的收益。这可以用于描述博弈的结果，其中每个个体的支付取决于他们自己的策略和其他个体的策略。
Determine the payoff matrix: for each pair of interactions between individuals, construct a payoff matrix that contains the benefits of each individual under different combinations of strategies. This can be used to characterize the outcome of the game, where the payoffs of each individual depend on their own strategy and the strategies of the other individuals.
3.演化动态：引入演化动态，例如以遗传算法为基础。每一代个体根据其在上一代中的成功程度被选择进行繁殖，并且他们的策略有一定的概率被变异。这模拟了生物学中的遗传机制。
3. evolutionary dynamics: evolutionary dynamics are introduced, e.g. based on genetic algorithms. Individuals of each generation are selected for reproduction based on their level of success in the previous generation and their strategies have a certain probability of being mutated. This simulates genetic mechanisms in biology.
4.重复博弈：通过多代的演化动态，观察群体中策略的演变。随着时间的推移，某些策略可能会在群体中占据主导地位，而其他策略可能会被淘汰。
4. Repeated games: the evolution of strategies in a population is observed through the evolutionary dynamics of multiple generations. Over time, certain strategies may dominate the population while others may be eliminated.
5.分析演化稳定策略：研究演化的结果，特别是关注哪些策略在长期内稳定存在，形成了演化稳定策略。
5. Analyze evolutionary stable strategies: study the results of evolution, especially focusing on which strategies are stable in the long run and form evolutionary stable strategies.
演化博弈的一个重要概念是纳什均衡，即在一个给定的策略组合下，没有个体能够通过改变其策略来获得更好的支付。研究者通常关注演化博弈中是否存在演化稳定策略，以及这些稳定策略对群体动态的影响。
An important concept in evolutionary games is the Nash equilibrium, which means that no individual can obtain a better payout by changing his or her strategy for a given combination of strategies. Researchers usually focus on the existence of evolutionarily stable strategies in evolutionary games and the effect of these stable strategies on group dynamics.
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参考资料：Dpeel翻译
参考文献：
楼永,常宇星,郝凤霞.区块链技术对供应链金融的影响——基于三方博弈、动态演化博弈的视角[J].中国管理科学,2022,30(12):352-360.
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文字|Wei
排版|Wei
审核|许江越