# Event Knowledge Graph: A Review Based on Scientometric Analysis
## 4 Results and Discussion
### Journal Co-Citation Network Analysis  
The journal co-citation network is a network structure used to analyze and visualize citation exchanges and relevance between journals. In this network, each journal is represented as a node and the citation relationship between journals is represented as links connecting nodes. As shown in Figure 7, the journal co-citation network contains 124 nodes and 639 links. The larger the node size, the higher the number of event-knowledge-graph-related publications contributed by this journal. Table 6 lists the information of the top five journals with regard to the frequency of publications, including journal name, its newest impact factor, frequency of publications, and average year. It can be seen that the node of \"AAAI CONF ARTIF INTE\" (AAAI Conference on Artificial Intelligence) with the largest radius has the highest publication frequency of 61 and the average year of those publications is 2018. In the previous years, the event-knowledge-graph-related documents were published in journals such as \"IEEE Transactions on Knowledge and Data Engineering\" and \"IEEE Transactions on Pattern Analysis and Machine Intelligence\", which are all highly impacted and fall in the categories of computer science, knowledge engineering, and data mining. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Abbreviation** & **Full Name** & **Impact Factor** &
\begin{tabular}{c} **Frequency of** \\ **Publications** \\ \end{tabular} & **Average Year** \\ \hline AAAI CONF ARTIF INTE & AAAI Conference on Artificial Intelligence & Conference journal & 61 & 2018 \\  & IEEE Transactions on & & 8.9 & 52 & 2015 \\ IEEE T KNOWL DATA EN & Knowledge and Data & & & \\  & Engineering & & & \\  & IEEE Transactions on Pattern & & & \\ IEEE T PATTERN ANAL & Analysis and Machine & 23.6 & 35 & 2013 \\  & Intelligence & & & \\ J MACH LEARN RES & Journal of Machine Learning & 6.0 & 31 & 2014 \\ COMMUN ACM & Communications of the ACM & 22.7 & 29 & 2012 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The top five journals sorted by the frequency of publications for the years 2012 to 2022. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Cluster ID** & **Size** & **Silhouette** &
\begin{tabular}{c} **Mean** \\ **(Year)** \\ \end{tabular} & **Label (LLR)** \\ \hline
0 & 62 & 0.978 & 2017 &
\begin{tabular}{c} flow graph analysis; data flow; \\ online analysis \\ dependency; domain-specific \\ modeling; business process simulation \\ automatic loop detection; application \\ structure detection; performance \\ monitoring \\ causality-associated graph neural \\ network; bio-event extraction; news event \\ \end{tabular} \\
0 & 14 & 0.994 & 2012 &
\begin{tabular}{c} **Mean** \\ **(Year)** \\ \end{tabular} & **Label (LLR)** \\ \hline
0 & 62 & 0.978 & 2017 &
\begin{tabular}{c} flow graph analysis; data flow; \\ online analysis \\ dependency; domain-specific \\ modeling; business process simulation \\ automatic loop detection; application \\ structure detection; performance \\ monitoring \\ causality-associated graph neural \\ network; bio-event extraction; news event \\ \end{tabular} \\
0 & 14 & 0.994 & 2012 &
\begin{tabular}{c} **Frequency of** \\ **Publications** \\ \end{tabular} & **Average Year** \\ \hline \hline \end{tabular}
\end{table} 
Table 5: The summary of the clusters of author co-citation network. As shown in Figure 7, the outermost purple ring around the node indicates the betweenness centrality of the journal. The thicker the purple ring, the higher the betweenness centrality of the journal. Such a purple ring appears only when the betweenness centrality is larger than 0.1. The information of the top five journals with higher betweenness centrality in the journal co-citation network is presented in Table 7, including journal abbreviation, full name, impact factor, betweenness centrality score, and the average year of publications.