Although a planar pair might theoretically be included, this would impose no constraint and thus be equivalent to an opening in the kinematic chain.

尽管理论上还可以包括平面，但平面却不能加以约束，因此只相当于开式运动链。

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With the linear graph and adjacent matrix method of graph theory, the possible forms of this mechanism are discussed by analyzing that of kinematic chain with 4~8 links connected by planar low pair.

运用图论的线图和邻接矩阵方法从分析平面低副4～8杆运动链的可能形式出发，分析了以连杆为起始构件这类机构的可能有的形式。

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Although a planar pair might theoretically be included, this would impose no constraint and thus be equivalent to an opening in the kinematic chain.

尽管理论上还可以包括平面副，但平面副却不能加以约束，因此只相当于开式运动链。

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