替代定理要求在用电压源或电流源替代一个二端元件或单口网络前和替代后，电路都要存在惟一解答。

下面通过对某个电路的讨论来说明电路(模型)的惟一解问题以及任何利用计算机电路分析程序来研究电路的惟一解问题。从讨论中也可以加深对替代定理要求电路满足惟一解的认识。

-Alternative theorem require the use of voltage source or current source alternative to a two-terminal components or single-port network before and after the alternative, the circuit must be the only answer there. By following the discussion of a circuit to illustrate circuit (model) the only solution of the problem and any use of computer circuit analysis program to study the circuit the only solution of the problem. From the discussion can also learn more about the alternative theorem of circuit to meet the requirements of unique solution.