:- use_module(library(pfl)).

:- set_pfl_flag(solver,fove).
%:- set_pfl_flag(solver,bp), clpbn_horus:set_horus_flag(inf_alg,ve).
%:- set_pfl_flag(solver,bp), clpbn_horus:set_horus_flag(inf_alg,bp).
%:- set_pfl_flag(solver,bp), clpbn_horus:set_horus_flag(inf_alg,cbp).

:- yap_flag(write_strings, off).


friends(P1, P2) :-
    person(P1),
    person(P2),
    P1 \= P2.

person @ 3.

markov smokes(P)::[t,f] , cancer(P)::[t,f] ; [0.1, 0.2, 0.3, 0.4] ; [person(P)].

markov friend(P1,P2)::[t,f], smokes(P1)::[t,f], smokes(P2)::[t,f] ; [0.5, 0.6, 0.7, 0.8, 0.5, 0.6, 0.7, 0.8] ; [friends(P1, P2)].

?- smokes(person_1, t), smokes(person_2, f), friend(person_1, person_2, X).