title: Arrow notation in slice category
body: <blockquote>
    <p>If <code>CatC</code> is a category and A any object of <code>CatC</code>, the slice category <code>CatC</code>/A is described this way:</p>
    
    <p>SC-1 An object of <code>CatC</code>/A is an arrow <code>f: C -&gt; A</code> of <code>CatC</code> for some object C.</p>
    
    <p>SC-2 An arrow of <code>CatC</code>/A from <code>f: C -&gt; A</code> to <code>f': C' -&gt; A</code> is an arrow <code>h: C -&gt; C'</code> with the property that <code>f = f' . h</code>.</p>
    
    <p>SC-3 The composite of <code>h: f -&gt; f'</code> and <code>h': f -&gt; f''</code> is <code>h' . h</code>.</p>
  </blockquote>
  
  <p>What is the type of arrow in <code>CatC</code>/A? </p>
  
  <p><code>C -&gt; C</code>(object in <code>CatC</code> to object in <code>CatC</code>) or <code>f -&gt; f'</code>(object in <code>CatC</code>/A to object in <code>CatC</code>/A).</p>