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(1976).</ref> The main question is whether the lack of controllability or observability are generic with respect to the variable system parameters. In the framework of structural control the system parameters are either independent free variables or fixed zeros. This is consistent for models of physical systems since parameter values are never known exactly, with the exception of zero values which express the absence of interactions or connections.

(1976).</ref> The main question is whether the lack of controllability or observability are generic with respect to the variable system parameters. In the framework of structural control the system parameters are either independent free variables or fixed zeros. This is consistent for models of physical systems since parameter values are never known exactly, with the exception of zero values which express the absence of interactions or connections.

(1976年)。 / ref 主要的问题是，对于可变系统参数来说，缺乏可控性或可观测性是否是一般性的。在结构控制的框架下，系统参数可以是独立自由变量，也可以是固定零点。这对于物理系统的模型是一致的，因为参数值永远不会准确地知道，零值除外，零值表示交互或连接的缺失。

(1976年)。 / ref '''<font color="#32CD32">主要的问题是，对于可变系统参数来说，缺乏可控性或可观测性是否是一般性的。在结构控制的框架下，系统参数可以是独立自由变量，也可以是固定零点。这对于物理系统的模型是一致的，因为参数值永远不会准确地知道，零值除外，零值表示交互或连接的缺失。</font>

===Maximum Matching===

===Maximum Matching===