Disconnectivity and Relative Positions in Simultaneous Embeddings

Bläsius, Thomas and Rutter, Ignaz (2013) Disconnectivity and Relative Positions in Simultaneous Embeddings. In: 20th International Symposium, GD 2012, September 19-21, 2012 , pp. 31-42(Official URL: http://link.springer.com/chapter/10.1007/978-3-642...).

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For two planar graph $G^{\textcircled1}$ = ($V^{\textcircled1}$, $E^{\textcircled1}$) and $G^{\textcircled2}$ = ($V^{\textcircled2}$, $E^{\textcircled2}$) sharing a common subgraph G = $G^{\textcircled1}$ ∩ $G^{\textcircled2}$ the problem Simultaneous Embedding with Fixed Edges (SEFE) asks whether they admit planar drawings such that the common graph is drawn the same. Previous algorithms only work for cases where G is connected, and hence do not need to handle relative positions of connected components. We consider the problem where G, $G^{\textcircled1}$ and $G^{\textcircled2}$ are not necessarily connected. First, we show that a general instance of SEFE can be reduced in linear time to an equivalent instance where $V^{\textcircled1}$ = $V^{\textcircled2}$ and $G^{\textcircled1}$ and $G^{\textcircled2}$ are connected. Second, for the case where G consists of disjoint cycles, we introduce the CC-tree which represents all embeddings of G that extend to planar embeddings of $G^{\textcircled1}$. We show that CC-trees can be computed in linear time, and that their intersection is again a CC-tree. This yields a linear-time algorithm for SEFE if all k input graphs (possibly k>2) pairwise share the same set of disjoint cycles. These results, including the CC-tree, extend to the case where G consists of arbitrary connected components, each with a fixed embedding. Then the running time is O(n^2).

Item Type: Conference Paper
Additional Information: 10.1007/978-3-642-36763-2_4
Classifications: G Algorithms and Complexity > G.490 Embeddings
URI: http://gdea.informatik.uni-koeln.de/id/eprint/1295

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