domains
    material, nadpis, portrait = symbol

predicates
    shkatulka(material)
    portraitGold(nadpis)
    portraitSilver(nadpis)
    portraitLead(nadpis)
    find(portrait)

clauses
    shkatulka(gold).
    shkatulka(silver).
    shkatulka(lead).
    portraitGold(X) :- X = gold.
    portraitSilver(X) :- X \= silver.
    portraitLead(X) :- X \= gold.
    find(X) :-
        portraitGold(X), not(portraitSilver(X)), not(portraitLead(X));
        not(portraitGold(X)), portraitSilver(X), not(portraitLead(X));
        not(portraitGold(X)), not(portraitSilver(X)), portraitLead(X).

goal
    shkatulka(X), find(X),
    write("Portrait v ", X, " shkatulke"), nl.