title: Finding candidate keys for given relation
body: <pre><code>R = (A, B, C, D, E)
  </code></pre>
  <p>The functional dependencies are:</p>
  <pre><code>A -&gt; B
  ED -&gt; A
  BC -&gt; E
  </code></pre>
  <p>It then lists the candidate keys as:</p>
  <pre><code>ACD, BCD, CDE
  </code></pre>
  <p>How are these candidate keys derived from the above FDs?</p>
  <p>Similarly,</p>
  <pre><code>R = (A, B, C, D)
  </code></pre>
  <p>The functional dependencies are:</p>
  <pre><code>D -&gt; B 
  AB -&gt; D 
  AB -&gt; C 
  C -&gt; A
  </code></pre>
  <p>It then lists the candidate keys as:</p>
  <pre><code>AB, BC, CD, AD
  </code></pre>
  <p>Again, my issue here is that I'm not sure how the candidate keys have been derived from the FDs.</p>