What we are saying is basically ‘any interaction between any parties can (should) be described with a currency (parties refers to any division ie n)’.
This is probably what this equation introduces* (also with a perspective “variable”): http://web.math.princeton.edu/jfnj/texts_and_graphics/Main.Content/An_Interesting_Equation_and_An_Interesting_Possibility/An_Interesting_Equation/Equation.general.vac/From.PennState/intereq.r.pdf
*or what it should be seen to introduce
