c</a>):</p>
<pre><code class="language-clojure">(defaxiom excluded-middle-ax
  "..."
  [[A :type]]
  (or A (not A)))
</code></pre>
<p>So for example a reference <code>(or (&gt; x 3) (not (&gt; x 3)))</code> can be considered inhabited (hence true), even though there is no underlying lambda-calculus term.</p>
<p>In the case of a theorem, then it is a little bit the same except that if a proof term is available then we could, in theory, consider the theorem as a definition and replace the reference term by th