Complex networks can be represented in a variety of ways. They can be decomposed into trees or sim-
ple networks, and these simpler structures can then be represented using one of the techniques just
described. Alternatively, they can be represented directly using indexes. Linked lists are not used by any
DBMS product to represent complex networks directly. In practice, complex networks are nearly always
decomposed into simpler structures, so we consider only those representations using decomposition.