Proof of the Chua conjecture on LTC-realizable resistive n-ports

In a recent paper Chua proved that a large class of voltage-controlled nonlinear resistive
n
-ports could be realized with the aid of a homeomorphic resistive
n
-port and a linear transformation converter (LTC) constructed of
2n
negative linear resistors. He conjectured that only
n
such resistors are needed. In addition to proving this conjecture, we demonstrate that the
n
resistors need not be negative.