We study the following maximization problem in the Euclidean plane: Given a collection of neighborhoods (polygonal regions) in the plane, the goal is to select a point in each neighborhood so that the longest spanning tree on selected points has maximum length. It is not known whether or not this problem is NP-hard. We present an approximation algorithm with ratio 0.548 for this problem. This improves the previous best known ratio of 0.511. The presented algorithm takes linear time after computing a diameter. Even though our algorithm itself is fairly simple, its analysis is rather involved. In some part we deal with a minimization problem with multiple variables. We use a sequence of geometric transformations to reduce the number of variables and simplify the analysis.
@InProceedings{biniaz:LIPIcs.ISAAC.2021.7, author = {Biniaz, Ahmad}, title = {{Approximating Longest Spanning Tree with Neighborhoods}}, booktitle = {32nd International Symposium on Algorithms and Computation (ISAAC 2021)}, pages = {7:1--7:11}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-214-3}, ISSN = {1868-8969}, year = {2021}, volume = {212}, editor = {Ahn, Hee-Kap and Sadakane, Kunihiko}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ISAAC.2021.7}, URN = {urn:nbn:de:0030-drops-154401}, doi = {10.4230/LIPIcs.ISAAC.2021.7}, annote = {Keywords: Euclidean maximum spanning tree, spanning tree with neighborhoods, approximation algorithms} }
Feedback for Dagstuhl Publishing