Electrical and electronic engineers are familiar with the impedance concepts of electric networks. In such networks the parameters of interest are impedances, admittances, currents, voltages, and other related attributes. As early as 1932, Foster1 in a classic paper recognized that the electric network is a special class of a more general class of oriented graphs and geometrical circuits. More recently, Shannon,2 Von Neumann,3 Mason,4,5 and others have shown that network and circuit concepts can be profitably applied to a large variety of problems, for example, the design and the analysis of switching circuits, the solution of problems in probability, the analysis of functional relationships, etc.