Grammatical Picture Generation
A Tree-Based Approach
Frank Drewes

How to explore the contents of the CD
The pages referred to by the links Chapter 2–8 and Appendix A on the main page contain all examples of the book (including those which appear in exercises). If you do not want to proceed by trial and error, you need a certain minimum knowledge regarding TREEBAG. A list of brief instructions which may suffice for the impatient is given here. For more information, read Chapter 8 of Grammatical Picture Generation or the even more detailed TREEBAG manual. (The TREEBAG version described in the book is version 1.5 while the one used here is version 1.6. However, the only visible difference is that the control panes of components are now shown in a common window rather than cluttering the screen with lots of small individual windows.)

There are two major ways in which you can explore the examples on the CD:

1. The easier, but more restricted possibility is to use a web browser in order to start TREEBAG by clicking on the link for the desired example. TREEBAG will then be executed as an applet and the example will be loaded. If you are lucky, you will not have to do anything to make it work.

   The applets have been tested successfully for all available combinations of Linux, Solaris, Mac OS X, and Windows XP with the browsers of the Mozilla family, Internet Explorer, Safari, and Galeon. If you encounter problems, the following may be the reason:

   1. To be able to execute TREEBAG, the browser needs the Java plug-in (version 1.4.2 or later). If TREEBAG does not start at all or does not run properly, you should check whether this plug-in is installed and works correctly. For browsers from the Mozilla family, information on how to install the Java plug-in can, at the time of this writing, be found at `http://plugindoc.mozdev.org/`. Unfortunately, it is sometimes not very easy do identify and eliminate problems with the Java plug-in as the browser may claim that the right version is installed and works properly. A way to check this is to try out some of the demo applets that can be found in Sun's Java distribution.
   2. If the main window of TREEBAG appears, but TREEBAG does not work properly (e.g., no worksheet is loaded), it may be necessary to create a Java policy that explicitly grants TREEBAG the local access rights it needs. It should actually work without, but maybe your browser is more restrictive than it should be? (You definitely need to create a Java policy if you want to modify examples, since you can neither save them to nor load them from your local file system unless TREEBAG is granted read and write access.)

   Notes:

   - Since most examples exhibit an exponential behaviour, it is not at all difficult to reach the limits of the standard memory and stack sizes of the Java plug-in. Unfortunately, some browsers do not seem to issue any message if the memory limit is exceeded – you just do not get the expected result. The Java 2 Platform includes a tool called `ControlPanel` that can be used to increase the standard values by passing options to the Java virtual machine. (On Mac OS X, this has been replaced with a similar tool found in the Java subdirectory of the folder `Applications/Utilities` – at least in version 10.4.) The options I typically use are `-Xss8m` (8MB stack space) and `-Xmx800m` (800MB memory limit).
   - Only one copy of TREEBAG at a time can be executed as an applet. As soon as you start another one, the currently active applet will be terminated.
2. If you want to modify the examples or generate PostScript output it is recommended to install TREEBAG as a stand-alone application on your system and copy the examples to the hard disk. This is not difficult (see the installation instructions) and may, as a pleasant side effect, result in a considerable performance improvement.

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