The invented method includes one or more of the following aspects of selecting a multiplicity of nodes, deriving a designator for each node of the multiplicity of nodes and associating each designator in a one-to-one correspondence with a respective node from which a respective designator is derived, each designator indicating a plurality of dimensional values, and each dimensional value expressing a quality of a variate property of an associated node, selecting a unique designator having a particular pattern of dimensional values, selecting a first node having a first node designator matching the particular pattern of dimensional values, and when no node is found to have the particular pattern of dimensional values expressed in the respective designator to be connected by an edge to an external node, reporting a positive finding of an island.