The term "cluster" denotes a collection of objects grouped by a specified relation, and its precise meaning depends on context.
In percolation theory, a cluster is a connected component of occupied sites or bonds. For a square point
lattice with nearest-neighbor adjacency, it is a group of filled cells connected
through vertical or horizontal neighbors.
In cluster analysis, a cluster is a group of data elements that are comparatively close according to a chosen distance
or dissimilarity measure. In cluster sampling,
a cluster is a group of population units that may be selected and observed together.
-tuple of algebraically
independent cluster variables belonging to
one seed.
