object agency : travel {\fbox{agency}
agency() :- accept( any ), agency(). book(X,Y) :- reachable(X), price(X,Y). price(amsterdam,5). \$...\$ }
Inheritance in DLP conforms to the subsumption relation for logical theories, in that it extends the functionality of a given object in a strict manner. DLP allows for multiple inheritance and even checks for cycles to protect the user from repetitions or cycles in the inheritance chain.