19.2 Hierarchical CYBERMAP Example - News Selection

To test the hierarchical CYBERMAP, we have built a system for filtering news messages. The system is based on the CM-2 version of the CYBERMAP implementation. It automatically downloads the daily political news messages of the "clari.news...." newsgroups into a HyperCard stack. A single mouse click (and the availability of the Connection Machine) generates the hierarchical CYBERMAP.

Figure I.111 displays the top-level CYBERMAP window of the news messages of a day (in the top left corner) and one article of the news stack in the background.

Figure I.111 Top-level CYBERMAP for news example

By clicking the hyperdrawers of the CYBERMAP, readers get either a pop-up menu listing all the nodes in the hyperdrawer (figure I.112), or can bring up a new CYBERMAP (figure I.113).

Figure I.112 Top-level CYBERMAP

Figure I.113 Selecting lower-level CYBERMAP from top-level CYBERMAP

In figure I.113 the lower-level CYBERMAP number 6 has been brought up. In figure I.114 the reader selects a hyperdrawer about a European summit and turmoil.

Figure I.114 Lower-level CYBERMAP

Figure I.115 Selecting a particular article of the hyperdrawer

Figure I.116 displays the article about the European summit, as well as browsing options for this hyperdrawer. Using the "right" and "left"-arrows of the browsing window in the top left corner of figure I.116, the user can sequentially browse all the articles of the current hyperdrawer.

Figure I.116 Browsing the selected articles of the hyperdrawer

The example in this section illustrates the real world usage of CYBERMAP. It would be very time consuming for readers to select the messages they are interested in by sequential reading. CYBERMAP offers an easier way to get a quick overview. It allows either browsing, by examining a few articles per topic, or in-depth reading, by sequential reading of the articles in the hyperdrawers of lower-level CYBERMAPs. We found this feature very useful and have therefore extended the current versions of CYBERMAP to include hierarchies of maps.

Until now we have concentrated on the clustering aspects of the CYBERMAP system. In the next chapter we focus on the problem of finding an optimal layout for hyperdrawers on the screen. We will present an algorithm based on minimum spanning trees, which can be used either for clustering related nodes, or for the layout of related nodes on the screen, or for both. Compared to the original CYBERMAP system, the new algorithm, which we have called "cybertree", offers better performance, but less flexibility.