title: Trivial No in Prolog returns Yes
body: <p>I have a  simple predicate in prolog that when MaxScore >0, it gives yes, otherwise is no. So if MaxScore is 0, then obviously the result is No. But this doesn't happen. Look closer at this: <img src="https://i.stack.imgur.com/pNE3o.png" alt="https://dl.dropbox.com/u/18710637/prologIsInsane.png"></p>
  
  <p>Or corresponding code:</p>
  
  <pre><code>aiPlay(PlayerNum, Board, Pos, BotType) :-
      aiTryAll(Board, PlayerNum, ScoreList, 0),
      scoreListGetPos(ScoreList, 1, Pos, MaxScore),
      write('MaxScore: '), write(MaxScore), nl,
      MaxScore &gt; 0.
  </code></pre>
  
  <p>And corresponding output:</p>
  
  <pre><code>| ? myQuery(Pos).
  MaxScore: 0
  MaxScore: 0
  MaxScore: 1
  Pos = 6 ?
  yes
  | ?
  </code></pre>
  
  <p>I am getting insane with this. Anyone have a clue about what is happening?</p>