# Hot Topic Community Discovery on Cross Social Networks
## 4 Experiment and Results
### Hot Topic Community Discovery
#### 4.3.4 Hot Topic Community Results and Analysis  
Figure 13 shows the result of hot topic communities clustered by spectral clustering algorithm, which performs best in the four clustering algorithms. For better display, the top 10 most frequently occurring topic labels are chosen in each hot topic community. Table 3 shows some of the topic labels in hot topic communities. Figure 12: The Silhouette Coefficients of different clustering algorithm. The hot topic communities in the first quarter are mainly focused on entertainment topics due to the new year and spring festival. In the second quarter, the earthquake in Japan becomes the focus of attention. Hot topics are mainly focused on social events in the third quarter, such as \"Libyan [PERSON] arrested\", \"[PERSON] incident \", \"Rainstorm in Guangdong\" etc. In the fourth quarter, the 100 th anniversary of the 1911 Revolution turns into a new hot topic. \begin{table}
\begin{tabular}{c c} \hline \hline
**Time** & **Part of Frequently Occurring Topic Labels** \\ \hline
1 st Quarter & singing party, new song, Chinese pop, Hollywood, music scene, ceremony, cold wind, poster, earn money, cooperation, cultural exchange, spring festival, commerce \\ \hline
2 nd Quarter & **Japan**, radioactivity, **casualties**, **earthquake**, **refugee**, foreboding, resignation, opposition, snow, demonstration, **biota**, **fuel**, fire accident, indiscriminate charging \\ \hline
3 rd Quarter & **Libyan**, **weapon**, **[PERSON]**, **kill**, Red Cross, director, **military**, base interest, country, **Ministry of Culture**, **condem**, money, celebrate, central weather station \\ \hline
4 th Quarter & **1911 Revolution, 100 years**, **Wuchang**, **army**, challenge, commemorate, **government**, Prime Minister rain, Guangdong, tropical storm, risk, disaster relief \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Part of frequently occurring topic labels. Figure 13: Hot topic community results in different quarters. To verify our topic discovery results, we found the hot news of 2011 summarized by the Xinhua News Agency ([[http://www.xinhuanet.com/2011](http://www.xinhuanet.com/2011) xwfyb/]([http://www.xinhuanet.com/2011](http://www.xinhuanet.com/2011) xwfyb/)). Some of the news is shown in Table 4. The news \"The Ningbo--Wenzhou railway traffic accident\", \"The celebration of 1911 Revolution\", \"Earthquake happened in Japan\", \"[PERSON] was captured and killed\", \"NATO bombs Libya\" etc. have been discovered in our hot topic communities. We have bolded the topics in Table 3 and related events in Table 4. As we can see, in the first quarter, we find no hot topic communities related to hot news. We think that it is because the hot topics that we find are generally related to the Spring Festival, but the Spring Festival really cannot be considered as annual news. However, in reality, Spring Festival must be a hot topic in the first quarter in China. To verify the effectiveness of cross social networks, we conducted an experiment on each social network. Considering that the data volume of each social network is not large, we did not divide it into quarters like cross social networks. The result of the hot topics is shown in Table 5 and topics mentioned in the result of cross social networks are bolded. As we can see, the hot topics from each social network are part of hot topics from cross social networks. Certainly, hot topics from each social network also contain the topics that are not mentioned in our pervious result. This is because these topics are hot topics in the current social network, but cannot be regarded as hot topics in the cross social network. Sina Weibo and Netease News contains more hot topics and QQ Zone contains fewer hot topics. This is because hot topics are usually associated with major events. Information from Sina Weibo and Netease News usually relate to these events and data from QQ Zone is usually associated with daily life. Compared with daily life, social events are more likely to be hot topics.