title: . or operator expected after expression in GNU Prolog
body: <p>I have written a simple program to find largest of two number in prolog</p>
  
  <pre><code>domains
      x,y,z=integer
  predicates
      bigger(x,y,z)
  clauses
      bigger(X,Y,Z):-
          X&gt;Y,Z=X.
      bigger(X,Y,Z):-
          X&lt;Y,Z=Y.
  goal
      bigger(5,7,X).
  </code></pre>
  
  <p>but whenever I run the program I get the error:</p>
  
  <pre><code>compiling /home/prabin/large_number.pl for byte code...
  /home/prabin/large_number.pl:2:5: syntax error: . or operator expected after expression
  /home/prabin/large_number.pl:11:5: syntax error: . or operator expected after expression
      2 error(s)
  compilation failed
  </code></pre>
  
  <p>Why is it so?</p>