We investigate the practicality of approximation schemes for optimization problems in planargraphs based on balanced separators. The first polynomial-time approximation schemes (PTASes) for problems in planargraphs ...
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ISBN:
(数字)9783030340292
ISBN:
(纸本)9783030340292;9783030340285
We investigate the practicality of approximation schemes for optimization problems in planargraphs based on balanced separators. The first polynomial-time approximation schemes (PTASes) for problems in planargraphs were based on balanced separators, wherein graphs are recursively decomposed into small enough pieces in which optimal solutions can be found by brute force or other methods. However, this technique was supplanted by the more modern and (theoretically) more efficient approach of decomposing a planargraph into graphs of bounded treewidth, in which optimal solutions are found by dynamic programming. While the latter approach has been tested experimentally, the former approach has not. To test the separator-based method, we examine the minimum feed-back vertex set (FVS) problem in planargraphs. We propose a new, simple O(n log n)-time approximation scheme for FVS using balanced separators and a linear kernel. The linear kernel reduces the size of the graph to be linear in the size of the optimal solution. In doing so, we correct a reduction rule in Bonamy and Kowalik's linear kernel [11] for FVS. We implemented this PTAS and evaluated its performance on large synthetic and real-world planargraphs. Unlike earlier planar PTAS engineering results [8,36], our implementation guarantees the theoretical error bounds on all tested graphs.
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