## 3 Results
### Experiment and Analysis  
#### 3.2.1 Verify the Incentive Negative Decay Mechanism  
A collaboration evaluation example is used to observe the acquisition of incentive scores of collaborative edge devices with different positive degrees. In this experiment, we \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **Description** & **Value** \\ \hline \(R_{b}\) & Basic cooperative reward score & 20 \\ \(\theta_{q}\) & Baseline quality reward score & 10 \\ \(\varphi_{1}\) & The quality threshold of collaborative trust evaluation task & 0.2 \\ \(\varphi_{2}\) & The quality threshold of collaborative trust evaluation task & 0.5 \\ \(\theta_{e}\) & Baseline efficiency reward score & 10 \\ \(\tau_{max}\) & The maximum completion time of cooperative trust evaluation task & 5 (min) \\ \(\tau_{dmax}\) & The maximum decay time & 48 (h) \\ \(\tau_{d}\) & Decay time interval & 1 (h) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Simulation Parameters. set the time of a single collaborative trust evaluation task as 4 h. Based on the incentive scores obtained after successful collaboration, the score is 20. Since the collaborative edge device needs to exchange incentive scores for computing resources and collaboration help provided by CEEC, we simply set the consumption as one incentive score per hour and we set the running time of the instance to the maximum decay time \(\tau_{\text{dmax}}\), 48 h. In order to show the effect of the incentive negative decay mechanism directly and concisely, participating cooperation and negative cooperation are carried out alternately, which shows that the cooperative edge device intermittently participates in the cooperative trust evaluation task. In Figures 7 and 8, the negative collaboration time of the edge device is set as 1 h, 2 h, 3 h, 6 h, 12 h, 16 h and 20 h. The red time period represents when the edge device is participating in the collaboration trust evaluation task, and the blue time period represents when the edge device is in a negative state. It can be seen from Figure 7a that when the collaborative edge device continuously participates in the collaborative trust evaluation task, its incentive score will increase in a stepwise way and a large number of incentive scores can provide the edge device with more computing resources and collaboration help from CEEC. According to Figure 7b,c, when the negative cooperation duration is short (between 0 and 2 h), the edge device can still maintain the reserve of incentive scores by intermittently participating in the cooperative trust evaluation task. According to Figures 7d and 8a, when the negative collaboration  
Figure 7: Comparison of incentive score with different negative collaboration time(red: positive, blue: negative): (**a**) Edge devices that continuously collaborate actively; (**b**) Edge devices that passively collaborate for 1 h; (**c**) Edge devices that passively collaborate for 2 h; (**d**) Edge devices that passively collaborate for 3 h.  
duration gradually increases (between 2 and 6 h), the incentive score obtained by the edge device is no longer enough to compensate for the negative attenuation effect caused by the negative collaboration although the edge device participates in the collaboration trust evaluation task intermittently. At this time, with the continuous decay of the incentive score, the edge device receives the incentive, so it needs to actively participate in the cooperative trust evaluation task to re-enhance the reserve of incentive scores. According to Figures 7d and 8a, when the negative cooperation duration increases to the mid-decay stage (between 6 and 16 h), the incentive score of the edge device will approach 0 with continuous decay. The edge device needs to increase the positivity towards participating in the collaborative trust evaluation task in the mid-decay stage or it will become a negative edge device.