## 4 Results and Discussion
### Network Topology Feature Analysis  
(1) Degree  
The degree of a node in a complex network is one of the most important and fundamental features for analyzing the network topology. In the developed interaction network of seafarers' unsafe acts and their influencing factors, the degree of a node is the number of seafarers' unsafe acts and their influencing factors that directly connected to other seafarers' unsafe acts and their influencing factors. The degree of a node reflects the direct influence of the node in the network, the more connections a node has, the greater the influence of that node in the network. The in-degree, out-degree, and total degree values of the nodes in the interaction network of seafarers' unsafe acts and their influencing factors are shown in Figure 6.  
Figure 4: Scatter plot of 260 association rules. Figure 5: Interaction network of seafarers’ unsafe acts and the influencing factors. It can be seen that the nodes with high in-degree values include failure to determine the risk (U31), failure to take effective collision avoidance action early (U25), and failure to make proper sound and light signals (U16), which are significantly influenced by adjacent nodes and may lead to serious consequences. In particular, failure to determine the risk (U31) has the largest in-degree with a value of 22, but the out-degree value is only 5, indicating that there are 22 seafarers' unsafe acts and their influencing factors in the interaction network that can lead to seafarers' failure to determine the risk. On the other hand, the nodes with high out-degree values include lack of supervision and guidance (S2), inadequate safety management (S4), and lack of standardization (O7), which have a higher direct impact on adjacent nodes. The nodes with the highest total degree values are failure to determine the risk (U31) and lack of supervision and guidance (S2) with a degree value of 27, followed by inadequate safety management (S4) and failure to maintain proper lookout (U17). These nodes with high total degree values are key nodes in the interaction network, and taking proactive prevention of these influencing factors and seafarers' unsafe acts would effectively reduce the connectivity of the network. In addition, the average degree value of the network is 9.81, which indicates that each seafarers' unsafe act/influencing factor in the network is closely related to 9.81 other seafarers' unsafe acts/influencing factors on average, i.e., changes in each node in the interaction network would cause changes in an average of 9.81 nodes that have a direct effect relationship with that node. (2) Average path length  
The average path length of a network is the average of the shortest path lengths between all node pairs in the network. In the developed interaction network of seafarers' unsafe acts and their influencing factors, the average path length indicates the risk propagation rate of seafarers' unsafe acts and their influencing factors in the network. If the average path length of the network is shorter, it means that fewer intermediate nodes need to pass between nodes, indicating faster risk propagation rate of seafarers' unsafe acts and their influencing factors in the network. The average path length of the interaction network is 1.8048, which means that a change in any seafarers' unsafe act/influencing factor in the network would cause a change in other seafarers' unsafe act/influencing factor that is not adjacent to it by only 1.8048 steps on average. In addition, the diameter of the network is 5, which is the distance between the lack of supervision and guidance (S2) and insufficient utilization of bridge resources (P4), indicating that it takes at most 5 steps for any one seafarer's unsafe act/influencing factor to affect another seafarer's unsafe act/influencing factor in the interaction network. Figure 6: Degree of the nodes. (3) Clustering coefficient  
The clustering coefficient refers to the ratio of the adjacent nodes of the nodes in the network that are also connected to each other.