title: Understanding Functional Dependencies and equivalent relations
body: <p>So I am trying to learn and understand Functional Dependencies and it is very hard to find a clear definition online when it comes to equivalent relations. Can someone please give me a definition and examples on how they work? </p>
  
  <p>For example, if I have the relation </p>
  
  <pre><code>R(A,B,C,D) 
  </code></pre>
  
  <p>and a set </p>
  
  <pre><code>{AB-&gt;C, AC-&gt;B, AB-&gt;CD}. 
  </code></pre>
  
  <p>Would something like </p>
  
  <pre><code>{AB-&gt;C, AC-&gt;B, AB-&gt;C} 
  </code></pre>
  
  <p>be equivalent? </p>
  
  <p>I personally would think so because <code>AB-&gt;CD</code> to my understanding is the same as <code>AB-&gt; C and D</code>. </p>