# The ACL2 Books Directory

WARNING: This page is deprecated. As of early 2014, this file is mostly up-to-date. However, moving forward, we have decided to provide an "index" into the books through the xdoc manual. Thus, we recommend that instead of updating this file, that you use the xdoc system to document your book, and then include your book's documentation by adding it to books/doc/top.lisp.

If you particularly want to, you should feel free to add a pointer to your work in this file, but you shouldn't consider it to be the way of documenting your work that will reach the most people.

The word ``book'' has two senses to the ACL2 user. One is the normal one: a sequence of printed paper pages bound together between covers. There are such books about ACL2. Click here for more information.

The other sense is a technical one: an ACL2 ``book'' is a file of definitions, theorems and other commands used to extend ACL2's reasoning abilities. Commands add ``rules'' to ACL2's data base. When a book is ``certified,'' ACL2 checks that all the commands in it can be successfully processed. A book can be ``included'' into an ACL2 session to extend the data base. This is the standard way users exchange useful sets of theorems. See the online documentation topic BOOKS for details.

The standard distribution of ACL2 comes with many books. They are stored on this directory. This is a guide to the available books. We include instructions on how to certify the books in this directory at the end of this note.

Some of the links below are to files. Others are to directories. When you visit a directory, look at its `README` file. Most of these books were written by ACL2 users other than the authors of ACL2. Authorship is acknowledged in the individual files.

- GNUmakefile: a Unix file for recertifying all the books in this directory.
- Makefile-generic: a Unix file exploited by `GNUmakefile`.
- Makefile-subdirs: a Unix file exploited by `GNUmakefile`.
- Makefile-psubdirs: a Unix file exploited by `GNUmakefile`.
- Readme.html: this file.
- add-ons: books which add system-level functionality to ACL2; these should be considered experimental and potentially unsound.
- arithmetic: books about arithmetic. The book `books/arithmetic/top-with-meta.lisp` may be the most commonly used ACL2 arithmetic book. See the top of the README file in this directory for a discussion of arithmetic libraries you may want to use, in particular this one or arithmetic-5. Arithmetic is an extraordinarily rich topic and none of our books fully do it justice. If you develop an improved arithmetic book, let us know!
- arithmetic-5: books about arithmetic contributed by Robert Krug. The following older libraries are basically superseded by arithmetic-5 (see README files in each directory): arithmetic-2 and arithmetic-3.
- bdd: books that exercise ACL2's BDD mechanism.
- build: support for doing certification runs.
- ccg: automated termination analyisis.
- centaur: books contributed by Centaur formal verification folks; see `centaur/README`
- cgen: support for counterexample generation
- clause-processors: examples of the use of clause processors (e.g., external tools)
- coi: The coi books comprise a "shelf" of ACL2 books related to the modeling of "computational objects" such as processors, memories, kernels, microcode, and so on.
- cowles: support for arithmetic books
- cutil: Centaur Basic Utilities
- data-structures: books for common data structures, with utilities; see also subdirectory memories
- defexec: fast execution with mbe and defexec
- defsort: `defsort` defines a stable sort when given a comparison function
- demos: some demos
- finite-set-theory: finite sets in ACL2
- fix-cert: update relocated .cert files
- hacking: a library for those who wish to use trust tags to modify or extend core ACL2 behavior
- hints: tests of hints, especially `:or` and `:custom` hints
- ihs: ``integer hardware specification'', integer arithmetic appropriate for hardware modeling
- interface: utilities providing Emacs support for proof-trees and acl2-mode, as well as (obsolete?) infix printing.
- make-event: illustrations of `make-event`, which implements the idea of macros that can take state
- memoize: a descendant of the memoization scheme developed by Bob Boyer and Warren A. Hunt, Jr., which was incorporated into ACL2(h)
- meta: metafunctions for arithmetic
- misc: a grab-bag of useful books and utilities
- models: models, especially of digital systems, with associated proofs
- nonstd: books in support of reasoning about the real numbers in ACL2 using non-standard analysis. If you want this directory, you will need to download the gzipped tar file to your `acl2-sources/books/` directory, and then gunzip and extract it there.
- ordinals: books about ordinals
- oslib: operating system utilities
- parallel: example use of primitives for parallelism (with speed-up only in experimental extension that supports parallel evaluation)
- parsers: parsers
- powerlists: a data-structure suited to the analysis of recursive, data-parallel algorithms.
- projects: the following projects.
  - concurrent-programs: contributions by Sandip Ray (see Readme.lsp files in subdirectories)
  - equational: a deduction engine
  - leftist-trees: a heap-like data structure that can be used as a priority queue
  - legacy version of centaur/defrstobj/
  - milawa: a "self-verifying" theorem prover for an ACL2-like logic, developed by Jared Davis for his Ph.D. dissertation.
  - paco: Paco, a cut-down, simplified ACL2-like theorem prover for pedagogical use.
  - quadratic-reciprocity: Gauss's Law of Quadratic Reciprocity
  - projects/regex: a regular expression scanner implementation designed to be similar to GNU Grep
  - security: books supporting reasoning about security protocols
  - symbolic: generic proofs of partial and total correctness of sequential programs based on assertional reasoning
  - taspi: code relating to TASPI (Tree Analysis System for Phylogenetic Inference)
  - translators: translators
  - wp-gen: Weakest precondition generation and examples
- proofstyles: Soundness and completeness of different proof strategies used in sequential program verification, along with (in subdirectory `invclock`logical equivalence of two proof styles for verifying programs using operational semantics, namely inductive invariants and clock functions.
- rtl: floating-point arithmetic support, used for example in proofs about AMD rtl
- serialize: routines for serializing ACL2 objects to disk
- sorting: correctness and equivalence of several sort algorithms
- std: "standard" libraries being developed for ACL2
- str: a rudimentary string library for ACL2
- system: checks of invariants on the ACL2 logical world, and verification of termination and guards of some system functions; and, some system-related subdirectories.
- tau: support for the tau system
- textbook: solutions to the exercises in Computer-Aided Reasoning: An Approach
- tools: macros and tools designed to make common constructs easier and less verbose to write
- translators: translators to and from ACL2
- tutorial-problems: solutions to exercises of a tutorial nature
- unicode: help for reading input from files
- workshops: Books in support of ACL2 workshops, as listed just below. If you want this directory, you will need to download the gzipped tar file to your `acl2-sources/books/` directory, and then gunzip and extract it there.

- workshops/1999: books from ACL2 Workshop 1999, supporting and described in Computer-Aided Reasoning: ACL2 Case Studies, including full scripts for each case study and answers to all the exercises
- workshops/2000: books and papers from ACL2 Workshop 2000
- workshops/2002: books and papers from ACL2 Workshop 2002
- workshops/2003: books and papers from ACL2 Workshop 2003
- workshops/2004: books and papers from ACL2 Workshop 2004
- workshops/2006: books from ACL2 Workshop 2006
- workshops/2007: books from ACL2 Workshop 2007
- workshops/2009: books from ACL2 Workshop 2009
- workshops/2011: books from ACL2 Workshop 2011
- workshops/2013: books from ACL2 Workshop 2013
- workshops/2014: books from ACL2 Workshop 2014

- xdoc and xdoc-impl: prototype XML documentation system

If you seek a book you suspect someone might have created but which is not here, join the ACL2 mailing list and ask the community.

If you develop a book you think will be useful to the community, please submit it following the instructions for contributing books to ACL2.

## Certification Instructions

Instructions for certifying the ACL2 community books may be found in the folllowing ACL2 documentation topic: BOOKS-CERTIFICATION.

If you obtained your books from a gzipped tarfile (typically named `books-*.tar.gz`), as opposed to svn, then you don't yet have the workshops books. If you want them, simply download workshops.tar.gz to your acl2-sources/books/ directory, and then gunzip and extract it there.