prob joeW: 5/7.
prob williamW: 5/7.
prob jackW: 5/7.
prob averallW: 5/7.

works(joe) <- joeW.
works(william) <- williamW.
works(jack) <- jackW.
works(averall) <- averallW.

needs(joe, []).
needs(william, []).
needs(jack, [joe]).
needs(averall, [jack, william]).


burgels(X) <-
	works(X) & needs(X, Needs) & forall(member(Burgel, Needs), member(Burgel, Workers)).

%burgels(X) <-
%	works(X) & findall(Y, works(Y), Workers) &
%	needs(X, Needs) & forall(member(Burgel, Needs), member(Burgel, Workers)).

%findall(X, burgels(X), L) & length(L, LX) & LX > 1.