of clusters (only by infomap)

techniques such as multi-dimensional scaling (MDS) have *O(n3*

**Figure 5.** Interface of Mapping Science.

In the clustered view that opens when users click one of the areas in the portfolio view, the results of clustering all the articles and projects in the area are shown. The details of the clustering method are shown in the next section. This view is for taking a look at the technologies in the area. Each cluster has at most 10 labels, which are extracted as feature phrases using a probabilistic information retrieval method, BM25 [20].

In the analytic view that opens when users click one of the clusters in the clustered view, each node corresponds to a article or a project, and distances between the nodes are proportional to the cosine similarities between articles/projects, as much as possible. In addition, direct citation links between articles (citing → cited) are shown in light green edges with labels showing common phrases between two articles, which are also extracted by the BM25 method. When users click a node, the detailed information about the node (article or project) is shown on the map.

In all the views, the search box located at the upper-left corner provides full-text search for all articles and projects included in the current view, and the search results are highlighted in the view. Moreover, the analytic view provides the time-shift bar, which displays the cumulative changes in a cluster according to published/started years of articles/projects. The trial version of this map is publicly available at https://jipsti.jst.go.jp/foresight/.
