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can also be used, where are functions that compute other vertex invariants. It is expected that for each function , the call returns the corresponding invariant at vertex in graph . The functions are evaluated in order, and the evaluation stops either when all functions have been evaluated or when an empty equivalence class is found. Three vertex invariants, DegreesOf2Neighborhood, NumberOf2Paths, and Distances are Combinatorica functions and can be used to refine the equivalences.