vaxmacs is a major mode for emacs that allows you to count perfect matchings of bipartite planar graphs, compute placement probabilities, q-enumerations, and many other things. The planar graph is represented as an ASCII picture in an emacs buffer. In addition to computing properties of the graph, vaxmacs can help construct the ASCII representation, and can construct postscript of the graph. vaxmacs is self-documenting, once you have it running, typing ``?'' will cause it to explain how to use it.

vaxmacs requires GNU emacs 19, version 19.30 or later, or GNU emacs 20.
To compute dimer properties of the graphs, vaxmacs starts a maple process. It's possible that subsequent versions may be able to use other backend engines, but for now you need maple.

To install vaxmacs, click here to obtain vax.el. Then add the following lines to your .emacs file:
(setq auto-mode-alist (cons '("\\.vax$" . vax-mode) auto-mode-alist))
(autoload 'vax-mode (expand-file-name "~/vax.el") nil t)
This assumes you placed vax.el in your home directory. If you place it somewhere else, then you can replace the "~/vax.el" with the appropriate path.

If the command you type to start maple is something other than "maple", then you can add lines such as the following to your .emacs
(setq vax-mode-hook
'(lambda () (setq maple-command "/mit/tiling/bin/mapletty")))

Once you've installed vaxmacs, then whenever you open a file with a ``.vax'' filename extension, emacs will enter VAX mode, and you're in business.