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<head><title>An_Example_of_ACL2_in_Use.html -- ACL2 Version 3.1</title></head>
<body text=#000000 bgcolor="#FFFFFF">
<h2>An Example of ACL2 in Use</h2>
To introduce you to ACL2 we will consider the <code>app</code> function discussed
in the <a href="Common_Lisp.html">Common Lisp</a> page, <b>except</B> we will omit
for the moment the <b>declare</B> form, which in ACL2 is called a <b>guard</B>.
We will deal with guards later. <p>
Here is the definition again
<pre>
<b>(defun app (x y)</B>
<b>(cond ((endp x) y)</B>
<b>(t (cons (car x) </B>
<b>(app (cdr x) y)))))</B>
</pre>
<p>
<p>
<p>
The next few stops along the Walking Tour will show you
<pre>
* how to use the ACL2 documentation,
* what happens when the above definition is submitted to ACL2,
* what happens when you evaluate calls of <code>app</code>,
* what one simple theorem about <code>app</code> looks like,
* how ACL2 proves the theorem, and
* how that theorem can be used in another proof.
</pre>
Along the way we will talk about the <b>definitional principle</B>, <b>types</B>,
the ACL2 <b>read-eval-print loop</B>, and how the <b>theorem prover</B> works.<p>
When we complete this part of the tour we will introduce the notion of
<b>guards</B> and revisit several of the topics above in that context.<p>
<a href="How_To_Find_Out_about_ACL2_Functions.html"><img src=walking.gif></a>
<br><br><br><a href="acl2-doc.html"><img src="llogo.gif"></a> <a href="acl2-doc-index.html"><img src="index.gif"></a>
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