| strongly connected component (MDM) |
In the theory of directed graphs, a strongly connected component is the set of components of the graph, all of which are connected with complementary directed references (or edges). Each subcomponent of an SCC is connected in both directions via directed references with every other subcomponent of the SCC. More concretely, a subcomponent B of an SCC is always reachable via directed references from any subcomponent A of the SCC and vice versa.
From the perspective of other regions of a graph which have unidirectional references to one or more subcomponents of an SCC, the SCC appears to be unitary, a single component. A reference to one subcomponent of the SCC is a reference to all subcomponents of the SCC.
In practice, SCCs play an important role in the depiction of problems in the management of memory objects in main memory, as well as in representations of other problems. In memory management, a garbage collector must of course be able to recognize SCCs and manage them as units.
In ABAP, for example, an SCC can consist of instances of two classes, each of which possesses a reference to the other instance. If there is no unidirectional reference to either of the objects in the SCC, then the ABAP Garbage Collector will delete both objects of the SCC.