Two Mathematical Comments on the Thevenin Theorem: An “Algebraic Ideal” and the “Affine Nonlinearity”

Figure 2

(a) Any such “ladder-type” circuit, and even a much more complicated 1-port, can be equivalently (for the external circuitry) reduced to (b). and are easily calculated [1, 2]. So, (b) is the “ideal”; considering additions of linear elements to such a circuit as (b) as an interaction (i.e., a binary operation) with (b), we obtain the form of (b) again.

(a)

(b)