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arXiv 1904.12596cs.DS
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基于层次嵌入约束的图平面性测试

Graph Planarity Testing with Hierarchical Embedding Constraints

Giuseppe Liotta, Ignaz Rutter, Alessandra Tappini

摘要:

层次嵌入约束定义了一组允许的循环顺序的边缘事件的顶点图。这些约束表示在FPQ树。FPQ-树是PQ-树的变体,除了P-和Q-节点之外还包括F-节点。F节点表示固定的置换,即,它无法逆转。设$G$是一个图,使得$G$的每个顶点都配备有一组FPQ树,该FPQ树编码其关联边的层次嵌入约束。我们研究的问题,测试是否$G$承认一个平面嵌入,这样,对于每个顶点$v$的$G$,循环顺序的事件到$v$的边缘描述的至少一个FPQ树与~ $v$。我们证明了这个问题是固定参数易处理的双连通图,其中的参数是$G$的树宽和与$G$的每个顶点相关联的FPQ-树的数量。我们还证明了,如果仅用FPQ-树的数目来参数化,则该问题是NP-完全的,如果仅用树宽来参数化,则该问题是W[1]-困难的。除了其本身的有趣性之外,层次嵌入约束的平面性测试研究还可以用于解决其他平面性测试问题。特别是,我们将我们的技术应用于研究的NodeTrix平面性测试的聚类图。我们发现,NodeTrix平面性测试与固定的双方是固定参数的参数化时,参数化的集群的大小和树宽的多图通过折叠集群到单顶点,只要这个图是bconnected。

英文摘要:

Hierarchical embedding constraints define a set of allowed cyclic orders for the edges incident to the vertices of a graph. These constraints are expressed in terms of FPQ-trees. FPQ-trees are a variant of PQ-trees that includes F-nodes in addition to P- and to Q-nodes. An F-node represents a permutation that is fixed, i.e., it cannot be reversed. Let $G$ be a graph such that every vertex of $G$ is equipped with a set of FPQ-trees encoding hierarchical embedding constraints for its incident edges. We study the problem of testing whether $G$ admits a planar embedding such that, for each vertex $v$ of $G$, the cyclic order of the edges incident to $v$ is described by at least one of the FPQ-trees associated with~$v$. We prove that the problem is fixed-parameter tractable for biconnected graphs, where the parameters are the treewidth of $G$ and the number of FPQ-trees associated with every vertex of $G$. We also show that the problem is NP-complete if parameterized by the number of FPQ-trees only, and W[1]-hard if parameterized by the treewidth only. Besides being interesting on its own right, the study of planarity testing with hierarchical embedding constraints can be used to address other planarity testing problems. In particular, we apply our techniques to the study of NodeTrix planarity testing of clustered graphs. We show that NodeTrix planarity testing with fixed sides is fixed-parameter tractable when parameterized by the size of the clusters and by the treewidth of the multi-graph obtained by collapsing the clusters to single vertices, provided that this graph is biconnected.

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