Adjacency
The concept of adjacency implies that the spatial elements share a side or a boundary. The adjacency is called strict
if there is a boundary line in common; the adjacency is called broad if there is a vertex in common (cf. illustration
above).
It answers the following question: "What is next to what?"
However, the topology provides nuances in the concept of adjacency. It takes into account only the order in which the
spatial
elements are located away from the target device.
If the two objects are in contact, the adjacency is said to be of first order. If there is another object lying in between,
it
is called to be of second order etc. (cf. illustration below). The order of adjacency is of interest, for example in
transportation
to determine the number of transshipments required to move goods or people from one place to another.