title: Pattern #1 field #2 has constraint conflicts which make the pattern
body: <p>I would like to make this rule</p>
  <pre><code>
  (defrule practica-superada1
      (or
          (and
              (oav ?alumno p1 apto)
              (oav ?alumno p2 apto)
          )
          (and
              (oav ?alumno p1|p2 apto)
              (oav ?alumno trabajo ok)
          )
  
      )
      =>
      (assert (oav ?alumno practica superada))
  )
  </code></pre>
  <p>as this way:</p>
  <pre><code>
  (defrule practica-superada1
      (or
          (oav ?alumno p1&p2 apto)
          (and
              (oav ?alumno p1|p2 apto)
              (oav ?alumno trabajo ok)
          )
  
      )
      =>
      (assert (oav ?alumno practica superada))
  )
  </code></pre>
  <p>The first way it's OK. But the second it's not. I receive the error:</p>
  <p><code>Pattern #1 field #2 has constraint conflicts which make the pattern</code></p>
  <p>Could someone explain me the cause of this error?</p>