<div class="notebook"> <div class="nb-cell program" name="p1"> reduce([], _, N, N). reduce([X|Xs], Op, N, R) :- reduce(Xs, Op, N, R0), call(Op, X, R0, R). </div> <div class="nb-cell query" name="q1"> reduce([[a,b],[c,d],[e,f]], append, [], R). </div> </div>