e <code>Logical</code> concept. Let <code>a</code>, <code>b</code> and <code>c</code> be objects of a <code>Logical</code> data type, and let <code>t</code> and <code>f</code> be arbitrary <em>true-valued</em> and <em>false-valued</em> <code>Logical</code>s of that data type, respectively. Then, </p><div class="fragment"><div class="line"><span class="comment">// associativity</span></div>
<div class="line"><a class="code" href="group__group-_logical.html#ga68c00efbeb69339bfa157a78ebdd3f87">or_</a>(a, <a cl