Planarity Testing and Optimal Edge Insertion with Embedding Constraints
Many practical applications demand additional restrictions on an admissible planar embedding. In particular, constraints on the permitted (clockwise) order of the edges around a vertex, like so-called side constraints, abound. In this paper, we introduce a set of hierarchical embedding constraints that also comprises side constraints. We present linear time algorithms for testing if a graph is ec-planar, i.e., admits a planar embedding satisfying the given embedding constraints, as well as for computing such an embedding. Moreover, we characterize the set of all possible ec-planar embeddings and consider the problem of finding a planar combinatorial embedding of a planar graph such that an additional edge can be inserted with the minimum number of crossings; we show that this problem can still be solved in linear time under the additional restrictions of embedding constraints.
KeywordsPlanar Graph Linear Time Algorithm Expansion Graph Clockwise Order Planar Embedding
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