Lipkus uses a definition of Tanimoto similarity which is equivalent to formula_24, and refers to Tanimoto distance as the function formula_81. It is, however, made clear within the paper that the context is restricted by the use of a (positive) weighting vector formula_86 such that, for any vector "A" being considered, formula_87 Under these circumstances, the function is a proper distance metric, and so a set of vectors governed by such a weighting vector forms a metric space under this function.