NOTE8-UPDATE.html -- ACL2 Version 6.3

## NOTE8-UPDATE

ACL2 Version 1.8 (Summer, 1995) Notes

    Major Section:  RELEASE-NOTES

ACL2 can now use Ordered Binary Decision Diagram technology. See bdd. There is also a proof-checker `bdd` command.

ACL2 is now more respectful of the intention of the function `hide`. In particular, it is more careful not to dive inside any call of `hide` during equality substitution and case splitting.

The `ld` special (see ld) `ld-pre-eval-print` may now be used to turn off printing of input forms during processing of `encapsulate` and `certify-book` forms, by setting it to the value `:never`, i.e., `(set-ld-pre-eval-print :never state)`. See ld-pre-eval-print.

The TUTORIAL documentation section (now obsolete) has, with much help from Bill Young, been substantially improved to a bona fide introduction.

The term pretty-printer has been modified to introduce `(<= X Y)` as an abbreviation for `(not (< Y X))`.

Forward chaining and linear arithmetic now both benefit from the evaluation of ground subterms.

A new macro `set-inhibit-output-lst` has been defined. This should be used when setting the state global `inhibit-output-lst`; see set-inhibit-output-lst and see proof-tree.

The test for redundancy in definitions includes the guard and type declarations. See redundant-events.

See generalized-booleans for a discussion of a potential soundness problem for ACL2 related to the question: Which Common Lisp functions are known to return Boolean values?

Here we will put some less important changes, additions, and so on.

A bug has been fixed so that now, execution of `:comp t` (see comp) correctly handles non-standard characters.

A bug in `digit-char-p` has been fixed, so that the ``default'' is `nil` rather than `0`.

`True-listp` now tests the final `cdr` against `nil` using `eq` instead of `equal`, for improved efficiency. The logical meaning is, however, unchanged.

`Put-assoc-equal` has been added to the logic (it used to have `:``defun-mode` `:``program`, and has been documented.