assign(max_seconds, 30).

formulas(sos).
all x (Wolf(x) -> animal(x)).
all x (Fox(x) -> animal(x)).
all x (Bird(x) -> animal(x)).
all x (Caterpillar(x) -> animal(x)).
all x (Snail(x) -> animal(x)).
all x (Grain(x) -> plant(x)).

exists x Wolf(x).
exists x Fox(x).
exists x Bird(x).
exists x Caterpillar(x).
exists x Snail(x).
exists x Grain(x).

% All animals either eat all plants or eat all smaller animals that eat some plants.

all x (animal(x) -> (all y (plant(y)->eats(x,y)))
                    | 
                    (all z ( animal(z) &
                             Smaller(z,x) &
                             (exists u (plant(u) & eats(z,u)))
                            ->
                             eats(x,z)))).

all x all y (Caterpillar(x) & Bird(y) -> Smaller(x,y)).
all x all y (Snail(x) & Bird(y) -> Smaller(x,y)).
all x all y (Bird(x) & Fox(y) -> Smaller(x,y)).
all x all y (Fox(x) & Wolf(y) -> Smaller(x,y)).
all x all y (Bird(x) & Caterpillar(y) -> eats(x,y)).

all x (Caterpillar(x) -> (exists y (plant(y) & eats(x,y)))).
all x (Snail(x)       -> (exists y (plant(y) & eats(x,y)))).

all x all y (Wolf(x) & Fox(y) -> -eats(x,y)).
all x all y (Wolf(x) & Grain(y) -> -eats(x,y)).
all x all y (Bird(x) & Snail(y) -> -eats(x,y)).

end_of_list.

formulas(goals).

% There is an animal that eats {an animal that eats all grains}.

exists x exists y ( animal(x) &
	            animal(y) &
	            eats(x,y) &
                    (all z (Grain(z) -> eats(y,z)))).
end_of_list.