Collecting Microblog Posts Implicitly Related to Announcement Post

Events, festivals, and product releases are often announced via microblogs such as Twitter. Many users post messages that are related to these announcements. Such related posts are useful for both the senders of the announcements and users who are interested in public opinions of the announcements. However, it is not easy to collect such related posts because many are not explicitly related to the announcement post. In this paper, we propose a method for efficiently collecting such posts that are only implicitly related to an announcement post, taking into account retweets on Twitter in particular.