ACL2 (A Computational Logic for Applicative Common Lisp) is a software system consisting of a programming language, an extensible theory in a first-order logic, and a mechanical theorem prover. ACL2 is designed to support automated reasoning in inductive logical theories, mostly for the purpose of software and hardware verification. The input language and implementation of ACL2 are built on Common Lisp. ACL2 is free, open source (BSD license) software.
The ACL2 programming language is an applicative (side-effect free) variant of Common Lisp. ACL2 is untyped. All ACL2 functions are total — that is, every function maps each object in the ACL2 universe to another object in its universe.
ACL2's base theory axiomatizes the semantics of its programming language and its built-in functions. User definitions in the programming language that satisfy a definitional principle extend the theory in a way that maintains the theory's logical consistency.
The core of ACL2's theorem prover is based on term rewriting, and this core is extensible in that user-discovered theorems can be used as ad-hoc proof techniques for subsequent conjectures.
In my brain it's understood
You killed my soul like I knew you would
You hit me with your velvet touch
My sacrifice was all too much
Why did you have to walk away
On sacred ground yesterday
Fill my pride, you don't wanna know
Still inside, every time you go
You kill me
You took the breath right out of me
And now I find that I can't see
The shallow water is my grave
Now what I lost is what I crave
Fill my pride, you don't wanna know
Still inside, every time you go
You kill me
Now I can feel the ghost within
Don't put the curse on me again
Don't leave me in this golden cage
Until I live the final page
Fill my pride, you don't wanna know
Still inside, every time you go
You kill me
Fill my pride, you don't wanna know
Still inside, every time you go