/* Learning conc/3 with non-ground background knowledge */

background([conc/3,components/3]).
propositional([a([])]).

/* Examples of the target predicate */
conc(a([]),a([1,2,3]),a([1,2,3])).
conc(a([]),a([3]),a([3])).
conc(a([1,2]),a([3]),a([1,2,3])).
conc(a([2]),a([3]),a([2,3])).

/* Background knowledge for 3-element ordered lists */
components(a([Head|Tail]),a(Head),a(Tail)) :-
    sublist([Head|Tail],[1,2,3]).

sublist([H|T],[H|V]) :- sublist(T,V).
sublist(T,[_|V]) :- !, sublist(T,V).
sublist([],_).