contiguity

Contiguity is the property of being contiguous or in contact, typically describing objects, regions, or events that touch or lie beside one another. The term derives from Latin contiguus, meaning touching along a boundary.

In geography and cartography, contiguity denotes regions that share a common boundary. It is central to adjacency analyses, regional planning, and political redistricting. Contiguity can be defined by edge adjacency (shared boundary) or vertex adjacency (shared corner), and GIS tools often encode it in adjacency or contiguity matrices to study spatial relationships.

In statistics and probability theory, contiguity describes a relation between sequences of probability measures. A_n is contiguous to B_n if every sequence of events E_n with B_n(E_n) → 0 also satisfies A_n(E_n) → 0. The concept is used in asymptotic inference and Le Cam’s theory of experiments, helping to compare conclusions drawn from large samples.

In psychology, the law of contiguity states that events occurring near in time or space tend to become associated, supporting the formation of conditioned responses and memory links.

Etymology: contiguity from Latin contiguous, meaning touching together. Related notions include adjacency, adjacency matrices, and connectivity, depending on disciplinary context.