Series-Parallel Duality in the Mathematics of Appraisal

It has long been noticed that the basic functions in the mathematics of real estate appraisal and in financial arithmetic come in pairs where one function is the reciprocal of the other. For instance, the quot;payments to amortize a principal of onequot; is the reciprocal of the quot;principal amortized by payments of one.quot; This paper shows that this phenomenon is an example of the series-parallel duality ordinarily studied in electrical circuit theory and combinatorial mathematics