<div class="notebook"> <div class="nb-cell markdown" name="md1"> Part 1 * fact1/0 is red, since it is not called by any other predicate. Ok. * fact2/0 is black, since it is being called by rule3/0. Ok. * fact4/0 is red, although it is referenced by fact5/0 in Part 2. Pity. </div> <div class="nb-cell program" data-background="true" name="p1"> fact1. fact2. rule3 :- fact2. fact4. </div> <div class="nb-cell markdown" name="md2"> Part 2 * fact4/0 in rule5/0 is shown in "thin" red, suggesting that it is an undefined predicate. In fact, it is defined in Part 1. * fact6/0 in rule7/0 is shown in normal font, since it has been defined. </div> <div class="nb-cell program" data-background="true" name="p2"> rule5 :- fact4. fact6. rule7:- fact6. </div> </div>