]> African Wildlide Ontology, Semantic Web Primer, 4.3.1 pages 129-133 Animals form a class. Plants form a class disjoint from animals. Trees are a type of plant. Branches are parts of trees. Leaves are parts of branches. Herbivores are exactly those animals that eat only plants or parts of plants Carnivores are exactly those animals that eat also animals. Giraffes are herbivores, and they eat only leaves. Lions are animals that eat only herbivores. Plants eaten both by herbivores and carnivores