% Module loading
:- use_module(library(aleph)).

% Aleph initialization

:- if(current_predicate(use_rendering/1)).
:- use_rendering(prolog).
:- endif.
:- aleph.

% Mode declarations
% mode(RecallNumber,PredicateMode).
% - output
:- modeh(*,grandparent(+person,-person)).
:- modeb(*,father(+person,-person)).
:-determination(grandparent/2,father/2).

:-begin_bg.
person(john).
person(dad(john)).
person(dad(dad(john))).
person(jack).
person(dad(jack)).
person(dad(dad(jack))).
father(dad(john), john).
father(dad(dad(john)), dad(john)).
father(dad(jack), jack).
father(dad(dad(jack)), dad(jack)).
father(dad(X),X):-
    person(X).


:-dynamic grandparent/2.
:-end_bg.

:-begin_in_pos.
grandparent(john, dad(dad(john))).
grandparent(jack, dad(dad(jack))).
:-end_in_pos.

:-begin_in_neg.
grandparent(jack, dad(jack)).
grandparent(jack, john).
:-end_in_neg.

:-aleph_read_all.

[theory]

[Rule 1] [Pos cover = 1 Neg cover = 0]
grandparent(john,dad(dad(john))).

[Rule 2] [Pos cover = 1 Neg cover = 0]
grandparent(jack,dad(dad(jack))).

[time taken] [0.0]
[total clauses constructed] [2]
true.