<div class="notebook">

<div class="nb-cell program" data-background="true" name="p1">
:- dynamic(abnormal/1).
:- discontiguous(abnormal/1).
feathers(tweety).
flies(X) :- feathers(X), \+ abnormal(X).
</div>

<div class="nb-cell query" name="q1">
flies(tweety).
</div>

<div class="nb-cell program" data-background="true" name="p2">
abnormal(tweety).
</div>

<div class="nb-cell query" name="q2">
true,flies(tweety).
</div>

</div>