title: Candidate elimination algorithm lecture example
body: <p>I am looking through some lecture slides and cannot understand why the bold hypothesis at last G are just discarded, I can come to the same answer but don't understand why they're just discarded. </p>
  
  <pre><code>   sky           temperature         humidity
   |     |        |          |        |       |
  Sunny  Rainy      Warm       Coo     Normal   Low
  </code></pre>
  
  <p>and the set of positive and negative training examples:</p>
  
  <pre><code>    1.      ( S W N )+)
      2.      ( R C L )-)
      3 .     ( S C N )+)
      4.      ( S W L )-)
  </code></pre>
  
  <p>Training with the first example: ( S W N ) +)  generalizing…</p>
  
  <p>G = [( ? ? ? )]
  S = [( S W N )]</p>
  
  <p>Training with the second example: ( R C L ) -)  specializing…</p>
  
  <p>G = [( S ? ? ) ( ? W ? ) ( ? ? N )<br>
  S = [( S W N )]</p>
  
  <p>Training with the third example: ( S C N ) +) generalizing…</p>
  
  <p>G = [( S ? ? )( ? ? N )]                              <em>(the other is discarded )</em><br>
  S = [( S ? N )] </p>
  
  <p>Training with the fourth example: ( S W L ) -)  specializing…</p>
  
  <p>G = [<strong>( S C ? )</strong>( S ? N )<strong>( R ? N )(? C N)</strong>]  <em>(bold are discarded )</em><br>
  S = [( S ? N )]</p>
  
  <p>Convergence, the learned concept must be:  [( S ? N )]</p>