Distance Measures for Embedded Graphs
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We introduce new distance measures for comparing embedded graphs based on the Fréchet distance and the weak Fréchet distance. These distances take the combinatorial structure as well as the geometric embeddings of the graphs into account. Our distance measures are motivated by the comparison of road networks, for instance, to evaluate the quality of a map construction algorithm, a task for which suitable distance measures are currently missing. In this paper, we present a general algorithmic approach for computing these distances. Although we show that deciding the distances is NP-complete for general embedded graphs, we prove that our approach yields polynomial time algorithms for the distances based on the Fréchet distance if the graphs are trees, and for the distances based on the weak Fréchet distance if the graphs are trees or if they are plane. Furthermore, we prove that deciding the distances based on the Fréchet remains NP-complete for plane graphs and show how our general algorithmic approach yields an exponential time algorithm and a polynomial time approximation algorithm for this case.
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