using emacs with proof trees
Major Section:  PROOF-TREE

Within emacs, proof trees provide a sort of structure for the linear proof transcript output by the ACL2 prover. Below we explain how to get proof trees set up in your emacs environment.

To get started, it suffices to load the distributed ACL2 emacs file, which has lots more than just proof tree support (documented near the top of that file), as follows. Thus, you can put the following form in your ~/.emacs file, where DIR refers to your ACL2 source directory (typically called acl2-sources/).
(load "DIR/emacs/emacs-acl2.el")
Then you can start the proof tree display by issuing the following emacs command: M-x start-proof-tree.

If you prefer not to load the ACL2 emacs file as shown above, you can instead put the following forms in your ~/.emacs file (where DIR is as above) and then issue the above M-x command.

(setq *acl2-interface-dir*

(autoload 'start-proof-tree (concat *acl2-interface-dir* "top-start-shell-acl2") "Enable proof tree logging in a prooftree buffer." t)

Once the above is taken care of, then to start using proof trees you do two things. In emacs, start a shell (meta-x shell) and evaluate:
   M-x start-proof-tree
Also, in your ACL2, evaluate
If you want to turn off proof trees, evaluate this in emacs
   M-x stop-proof-tree
and evaluate this in your ACL2 session:
When you do M-x start-proof-tree for the first time in your emacs session, you will be prompted for some information. You can avoid the prompt by putting the following in your .emacs file. The defaults are as shown, but you can of course change them.
  (setq *acl2-proof-tree-height* 17)
  (setq *checkpoint-recenter-line* 3)
  (setq *mfm-buffer* "*shell*")
Alternatively, you can put the following in your ~/.emacs file in order to start proof trees without any queries.
  (start-proof-tree-noninteractive "*shell*")

Once you start proof trees (meta-x start-proof-tree), you will have defined the key bindings shown by executing C-z h in emacs. Also see proof-tree-bindings for that additional documentation.

If you want proof-trees to be displayed in a separate emacs frame to the side, then you can put the following forms in your .emacs file above the load of emacs-acl2.el described above. But you may wish to edit the second form, in particular the number 2048.

(start-proof-tree-noninteractive "*shell*")
(cond ((and (eq window-system 'x)
            (fboundp 'x-display-pixel-width)
            (= (x-display-pixel-width) 2048) ; for a wide monitor
       (if (boundp 'emacs-startup-hook) ; false in xemacs
           (push 'new-prooftree-frame emacs-startup-hook))))

The file interface/emacs/README-mouse.doc discusses an extension of ACL2 proof trees that allows the mouse to be used with menus. That extension may well work, but it is no longer supported. The basic proof tree interface, however, is supported and is what is described in detail elsewhere; see proof-tree. Thanks to Mike Smith for his major role in providing emacs support for proof trees.