Collecting ideas, thoughts, and information is important in a wide variety of fields. Visualizing this process enables you to identify networks, which makes it easier to evaluate and use the data. The English author Tony Buzan developed the principle of mind mapping for this purpose.

Compendium [1] is a powerful program for creating mind maps on the computer. The program doesn't just replace a notepad: At seminars in combination with a projector, you can create collaborative mind maps that you can then email directly to all participants.

Compendium is not included in the package sources of common distributions, so you need to download the current version from GitHub [2]. The program, written in Java, runs on any platform but requires a current Java Runtime Environment [3] on the system. To install, run the file you downloaded. The program is licensed under the GNU Lesser General Public License (LGPL), which you accept in the first screen. Next, select a target directory for the installation, ideally /opt/compendium/.

Now, you need to decide whether the installer should create an additional launcher (i.e., a corresponding script for Linux and Mac OS X or a batch file for Windows). In this way, if you install the software on a USB stick for use on different computers with different operating systems, you will always have the correct launcher at hand.

Before the installation begins, you can decide whether you want to create a shortcut in the Start menu. Just in case you want to remove the program later, the software also creates the Uninstaller/ subdirectory in the selected target directory, where you will find the appropriate program for the uninstall. Complete the installation by clicking on the Done button. The software is now ready for use.

Creating a Project

After the installation, you can either start Compendium by clicking on the shortcut or by using the

sh /<path to>/CompendiumNG.sh

command from the terminal. The first time you start the program, a small window appears in which you can call up instructions in a PDF file or watch movies with an introduction. Click on the New Project button to get started. In the dialog box that follows, enter a name for your project and specify a username and password (Figure 1).

Figure 1: If necessary, use the documentation provided, which comprises text files and several videos to get you started with Compendium. Alternatively, you can launch directly into a new project.

The next time the program is launched, Compendium displays a list of all projects on the computer. Select the one you want to continue working on and log in with its username and password. To manage users, open a dialog with Tools | User Manager. Use the Users tab to add users to the project.

If you work alone, use the options in the Single User System Options tab instead, and activate Set current user as default for this project. If the current project is the only one, also enable Set current database as default project for Compendium.

Nodes

Compendium stores information in nodes. Each new project already contains two such nodes: an Inbox and a Trash Bin. Users working together on a project can send each other messages within the program that then appear in the recipient's Inbox. Even if you're working alone on a project and don't use the Inbox, you cannot remove it from the desktop.

Node points and the information stored in them are first sent to the Trash when they are deleted. Double-clicking the icon opens the Trash Bin and displays all the information it contains. You then have the option of either restoring the information or deleting it permanently.

The software supports 10 types of nodes: Question, Answer, Map, List, Pro, Con, Reference, Note, Decision, and Argument. You can create a new node by right-clicking where you want to insert it. In the context menu, choose Create Node for the appropriate type and assign an intuitive name.

This basic principle applies to all nodes. The corresponding symbol with the name you assigned appears in the workspace. Double-clicking the icon opens a new dialog box in which you can save information. Depending on the type of node, the software displays and processes the data differently.

The node types Question, Answer, Pro, Con, Note, Argument, and Decision contain text. They only differ in appearance by their different icons, but they fulfill different purposes within the mind map.

The type of node can change during the development process of a map: For example, an Answer can turn into an Argument and later into a Decision. An asterisk at the top left of the node indicates that the node contains text. If you mouse over the asterisk, the program displays this text; double-clicking the icon lets you edit the text.

The Reference node type is used to include external information. After double-clicking, a dialog opens containing another text field for an external link, in addition to the usual text field. Enter a shortcut to a file on your computer or an address on the Internet.

For a file, you can decide whether the shortcut refers to the location of the file in the filesystem or whether Compendium stores a copy of the file in the project folder, which is useful if you use different computers to work on a project.

If you have a web page or a file format that Compendium recognizes, the link is automatically assigned an appropriate icon and double-clicking it opens the page or the file in the associated program (Figure 2). By clicking Tools | Linked Files Browser, you can see a list of all linked files and the locations in the filesystem.

Figure 2: In Compendium, you can include links to external content. If the program recognizes the linked file format, it displays a suitable icon and opens the external content in the correct program.

The Map and List nodes represent two different ways of displaying information. A Map is a mind map within a mind map, in which you arrange information on an area using nodes and connections as desired. However, the software displays the information as subitems in a list and offers you the option of sorting them according to certain criteria.

You can move and arrange nodes in the workspace as required. By right-clicking on a node, you can change its type with the Change Type To menu option (e.g., change it from Answer to Argument and then to Decision).

Networking

Compendium does much more than simply gather information in nodes: It lets you network information, providing an overview of interrelationships and facilitating evaluation. Networking can be created by means of graphical connections such as lines and arrows. Alternatively, you can use keywords to create context.

Graphical connections in the form of lines and arrows visualize relationships between nodes. Thus, an arrow from a study Reference to an Argument indicates that the paper supports the Argument. From the Argument, an arrow points to a Decision indicating that the Argument had an effect on it.

When you mouse over an existing node, you can create a graphical connection. A small arrow appears on each of the four sides of the node. A left-click on one of these arrows opens a selection menu listing the types of nodes. From this list, you select the kind of node you want to create and connect to the current node by dragging a line. The new node appears on the desktop, connected to the starting point by a line.

The line first appears as an unlabeled arrow from the new to the old node. You can adjust the appearance of the line by right-clicking on it and selecting the Contents menu item. A dialog box appears with a text field in which you can enter a description for the line, if desired. In the same dialog, you can select a color for the line from a list, where a certain color implies a certain meaning (e.g., Argument for, Argument against, Reply to, Report against, Further explanation, etc.). This association of colors with meanings simplifies the overview.

Later, you can change the text of a line by simply clicking on it and overwriting, and you can change the meaning of a line and its color assignment by right-clicking on the line. To assign a new meaning and color, select Change Type To and make the change. To adjust the direction of the arrows, right-click and select the Change Arrows To item.