Approximation Schemes for Planar Graph Connectivity Problems

Fuente: arXiv
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Auteurs principaux: Neuwohner, Meike, Traub, Vera, Zenklusen, Rico
Format: Preprint
Publié: 2025
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author Neuwohner, Meike
Traub, Vera
Zenklusen, Rico
author_facet Neuwohner, Meike
Traub, Vera
Zenklusen, Rico
contents Finding a smallest subgraph that is k-edge-connected, or augmenting a k-edge-connected graph with a smallest subset of given candidate edges to become (k+1)-edge-connected, are among the most fundamental Network Design problems. They are both APX-hard in general graphs. However, this hardness does not carry over to the planar setting, which is not well understood, except for very small values of k. One main obstacle in using standard decomposition techniques for planar graphs, like Baker's technique and extensions thereof, is that connectivity requirements are global (rather than local) properties that are not captured by existing frameworks. We present a novel, and arguably clean, decomposition technique for such classical connectivity problems on planar graphs. This technique immediately implies PTASs for the problems of finding a smallest k-edge-connected or k-vertex-connected spanning subgraph of a planar graph for arbitrary k. By leveraging structural results for minimally k-edge-connected graphs, we further obtain a PTAS for planar k-connectivity augmentation for any constant k. We complement this with an NP-hardness result, showing that our results are essentially optimal.
format Preprint
id arxiv_https___arxiv_org_abs_2512_21128
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Approximation Schemes for Planar Graph Connectivity Problems
Neuwohner, Meike
Traub, Vera
Zenklusen, Rico
Data Structures and Algorithms
Finding a smallest subgraph that is k-edge-connected, or augmenting a k-edge-connected graph with a smallest subset of given candidate edges to become (k+1)-edge-connected, are among the most fundamental Network Design problems. They are both APX-hard in general graphs. However, this hardness does not carry over to the planar setting, which is not well understood, except for very small values of k. One main obstacle in using standard decomposition techniques for planar graphs, like Baker's technique and extensions thereof, is that connectivity requirements are global (rather than local) properties that are not captured by existing frameworks. We present a novel, and arguably clean, decomposition technique for such classical connectivity problems on planar graphs. This technique immediately implies PTASs for the problems of finding a smallest k-edge-connected or k-vertex-connected spanning subgraph of a planar graph for arbitrary k. By leveraging structural results for minimally k-edge-connected graphs, we further obtain a PTAS for planar k-connectivity augmentation for any constant k. We complement this with an NP-hardness result, showing that our results are essentially optimal.
title Approximation Schemes for Planar Graph Connectivity Problems
topic Data Structures and Algorithms
url https://arxiv.org/abs/2512.21128