% Assuming % 1. Every fungus is a mushroom or a toadstool. % 2. Every boletus is a fungus. % 3. All toadstools are poisonous. % 4. No boletus is a mushroom. % 5. b is a boletus. % it follows that: % 6. b is poisonous. set(auto). list(usable). -fungus(x) | mushroom(x) | toadstool(x). -boletus(x) | fungus(x). -toadstool(x) | poisonous(x). -boletus(x) | -mushroom(x). boletus(b). -poisonous(b). end_of_list.