if two animals have the same food source then those two animals compete for food
animals is not food. two_person_game is not game_with_two_competitors. foe is rival. monogamy is relationship_between_two_people_or_animals. mate is animal. animals is food. monogamy is not relationship_between_two_people_or_animals. pair_of_animals is not pair. mate is not animal. pair_of_animals is pair.