I understand aggregation is a "whole/part" relationship, where the "parent" class is the whole and the "child" class is the part (and this is unidirectional), and that each class exist independently (as opposed to composition) But some examples I've seen are confusing me For instance, the path/segment relationship I understand the segmentThere is a fourth type, the manytoone relationship, however, that is just the reverse direction of the onetomany relationship This article introduces a design pattern for the manytomany relationship, and shows the UML class diagram which is You show a generalization relationship with a solid line with a closed arrow, pointing from the specific class to the general class 1 One class (the child class or subclass) can inherit attributes and operations from another (the parent class or superclass) The parent class is more general than the child class
Composite Pattern Wikipedia
