Ah. Zemanian et Yr. Chan, DOES A SERIES-PARALLEL NETWORK OF MONOTONE RESISTORS MAKE SENSE - YESOR NO, IEEE transactions on circuits and systems. 1, Fundamental theory andapplications, 44(1), 1997, pp. 45-54
A new procedure is presented that very rapidly determines whether or n
ot a dc operating point exists for a series-parallel network df contin
uous, strictly monotonically increasing resistances having possibly li
mited domains and/or ranges, This is accomplished without any attempte
d computation of the operating point, If such exists, it will be uniqu
e, The procedure does not involve any manipulation of the characterist
ic curves of the resistors other than the asymptotes to which they ten
d, As a result, it is easily programmed and rapidly executed, The test
is extendable to series-parallel networks of nonmonotonic resistors,
but in this case the test is only for existence-not for uniqueness.