## 3 Model and Analysis
### Problem Raising and Basic Assumptions
\begin{table}
\begin{tabular}{c p{142.3 pt}} \hline \hline
**Parameter** & **Definition and Explanation** \\ \hline \(E_{i}(i=\{X,Y,Z,U\})\) & Benefits of emission reductions when the agent implements an “abatement” strategy, such as economic benefits from reduced energy consumption and shorter construction periods. \\ \hline \(G_{i}(i=\{X,Y,Z,U\})\) & External damages faced by the agent when implementing a “no-abatement” strategy [28], such as fines from environmental protection authorities for exceeding emission standards and conflicts with the public due to environmental pollution. \\ \hline \(N_{i}(i=\{Y,Z,U\})\) & When X implements an “abatement” strategy, there is a contractual relationship with the downstream party \(i\), requiring \(i\) to pay a penalty to X for non-abatement. For example, a contractor’s failure to meet green construction requirements would necessitate payment of liquidated damages to the owner as per the agreement. \\ \hline \(C_{i}(i=\{X,Y,Z,U\})\) & Abatement costs are incurred by game players when implementing an “abatement” strategy. These include the cost of purchasing environmentally friendly materials and introducing advanced technology. \\ \hline \(\gamma_{i}(i=\{X,Y,Z,U\})\) & The efficiency of absorbing spillover information when the agent implements an “abatement” strategy [56]. This refers to the ratio of the amount of information related to emission reductions obtained by an agent to the total amount of information. \\ \hline \(\lambda_{i}(i=\{X,Y,Z,U\})\) & The transformative capacity of an agent to transform information into actual benefits when implementing an “abatement” strategy [56]. When the agent organizes and analyzes the data and decides whether to acquire technology, how much material to acquire, etc., it can lead to economic benefits. This indicator refers to the benefit the agent receives from the unit of information. \\ \hline \(\beta_{ij}(i=\{X,Y,Z,U\};i\
eq j)\) & Coefficient of value-added return on joint abatement by \(i\) for agent \(i\) when agent \(i\) and agent \(j\) implement “abatement” strategies simultaneously [36; 41]. \\ \hline \(a_{ij}(i=\{Y,Z,U\};j=\{X,Y,Z\};i\
eq j)\) & Coefficient of free-rider benefit can be obtained by \(i\) when the upstream party \(j\) implements an “abatement” strategy and the downstream party \(i\) implements a “no-abatement” approach, where \(\alpha_{ij}\leq\beta_{ij}\)[57; 58; 41]. \\ \hline \(J_{i}(i=\{X,Y,Z,U\})\) & Incentives received from the government, industry associations, etc., when the agent of the game implements an “abatement” strategy [34; 35], such as government green subsidies, industry honors, and awards. \\ \hline \(\Delta C_{i}(i=\{X,Y,Z,U\})\) & Costs can be reduced when the agent implements an “abatement” strategy with the assistance of external financial institutions, raw material markets, etc. [32; 33]. For example, carbon markets reduce carbon trading costs by waiving transaction fees, and banks reduce financing costs by shortening procedures. \\ \hline \(D\) & Content of knowledge, technology, and other information outside the PBSC relevant to carbon reduction [29; 30; 31], such as advanced technologies, incentives, and prices of environmentally friendly materials. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Parameters and definitions.