title: State defined by logical NOTs in Prolog
body: <p>How do I make a logical NOT in a predicate?<br>
  If I wanted to define a state dependent on three conditions, it might look like:  </p>
  
  <pre><code>test(A, B, C) :- cond(A), cond(B); cond(C).  
  </code></pre>
  
  <p>How would you define a state to be NOT A and NOT B and NOT C?</p>