Creative Commons Attribution 3.0 Unported license
A rectilinear Steiner tree for a set T of points in the plane is a tree which connects T using horizontal and vertical lines. In the Rectilinear Steiner Tree problem, input is a set T of n points in the Euclidean plane (R^2) and the goal is to find an rectilinear Steiner tree for T of smallest possible total length. A rectilinear Steiner arborecence for a set T of points and root r in T is a rectilinear Steiner tree S for T such that the path in S from r to any point t in T is a shortest path. In the Rectilinear Steiner Arborescense problem the input is a set T of n points in R^2, and a root r in T, the task is to find an rectilinear Steiner arborescence for T, rooted at r of smallest possible total length. In this paper, we give the first subexponential time algorithms for both problems. Our algorithms are deterministic and run in 2^{O(sqrt{n}log n)} time.
@InProceedings{fomin_et_al:LIPIcs.SoCG.2016.39,
author = {Fomin, Fedor and Kolay, Sudeshna and Lokshtanov, Daniel and Panolan, Fahad and Saurabh, Saket},
title = {{Subexponential Algorithms for Rectilinear Steiner Tree and Arborescence Problems}},
booktitle = {32nd International Symposium on Computational Geometry (SoCG 2016)},
pages = {39:1--39:15},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-009-5},
ISSN = {1868-8969},
year = {2016},
volume = {51},
editor = {Fekete, S\'{a}ndor and Lubiw, Anna},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.SoCG.2016.39},
URN = {urn:nbn:de:0030-drops-59310},
doi = {10.4230/LIPIcs.SoCG.2016.39},
annote = {Keywords: Rectilinear graphs, Steiner arborescence, parameterized algorithms}
}