NOTE-2-2.html -- ACL2 Version 6.3

## NOTE-2-2

ACL2 Version 2.2 (August, 1998) Notes

    Major Section:  RELEASE-NOTES

Important changes:

A bug was fixed in the compile command, `:comp`. The compiled code produced by `:comp` in previous versions could be wildly incorrect because of a confusion between the printer and the reader regarding what was the current Lisp `*package*`. This bug could manifest itself only if you used the `:comp` command to compile previously uncompiled functions while the current package was different from `"ACL2"`. What happened in that situation depended upon what symbols were imported into your current package. The most likely behavior is that the compiler would break or complain or the resulting compiled code would call functions that did not exist.

There have been no other important changes to the code.

However, this release contains some useful new books, notably those on the `books` subdirectories `cli-misc` and `ihs`. Both have `README` files. The `ihs` books provide support for integer hardware specifications. These books were crucial to Bishop Brock's successful modeling of the Motorola CAP. We thank Bishop for producing them and we thank all those who worked so hard to get these books released. We highly recommend the `ihs` books to those modeling ALUs and other arithmetic components of microprocessors or programming languages.

In previous versions of ACL2, the arithmetic books, found on `books/arithmetic/`, included the addition of several unproved axioms stating properties of the rationals that we believed could be derived from our ``official'' axioms but which we had not mechanically proved. The axioms were found in the book `rationals-with-axioms.lisp`, which was then used in the uppermost arithmetic books `top.lisp` and `top-with-meta.lisp`. John Cowles has now provided us with ACL2 proofs of those ``axioms'' and so in this release you will find both `rationals-with-axioms.lisp` and `rationals-with-axioms-proved.lisp`. The former is provided for compatibility's sake. The latter is identical but contains `defthm`s where the former contains `defaxiom`s. The top-most books have been rebuilt using ```-axioms-proved`'' book. Thanks John.

Less important notes:

Bishop Brock found a bug in `translated-acl2-unwind-protectp4`. Jun Sawada reported a bug in linear arithmetic that caused us not to prove certain trivial theorems concluding with `(not (equal i j))`. We have fixed both.

We now prohibit definitions that call certain event commands such as `DEFTHM` and `TABLE` because our Common Lisp implementations of them differ from their ACL2 meanings (so that compiled books can be loaded correctly and efficiently).

Minor bugs in the documentation were fixed.