Maximum Plane Trees in Multipartite Geometric Graphs
A geometric graph is a graph whose vertices are points in the plane and whose edges are straight-line segments between the points. A plane spanning tree in a geometric graph is a spanning tree that is non-crossing. Let R and B be two disjoint sets of points in the plane such that R ∪ B is in general...
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| Published in: | Algorithmica Vol. 81; no. 4; pp. 1512 - 1534 |
|---|---|
| Main Authors: | , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
New York
Springer US
01.04.2019
Springer Nature B.V |
| Subjects: | |
| ISSN: | 0178-4617, 1432-0541 |
| Online Access: | Get full text |
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| Summary: | A geometric graph is a graph whose vertices are points in the plane and whose edges are straight-line segments between the points. A plane spanning tree in a geometric graph is a spanning tree that is non-crossing. Let
R
and
B
be two disjoint sets of points in the plane such that
R
∪
B
is in general position, and let
n
=
|
R
∪
B
|
. Assume that the points of
R
are colored red and the points of
B
are colored blue. A bichromatic plane spanning tree is a plane spanning tree in the complete bipartite geometric graph with bipartition (
R
,
B
). In this paper we consider the maximum bichromatic plane spanning tree problem, which is the problem of computing a bichromatic plane spanning tree of maximum total edge length.
For the maximum bichromatic plane spanning tree problem, we present an approximation algorithm with ratio 1 / 4 that runs in
O
(
n
log
n
)
time.
We also consider the multicolored version of this problem where the input points are colored with
k
>
2
colors. We present an approximation algorithm that computes a plane spanning tree in a complete
k
-partite geometric graph, and whose ratio is 1 / 6 if
k
=
3
, and 1 / 8 if
k
⩾
4
.
We also revisit the special case of the problem where
k
=
n
, i.e., the problem of computing a maximum plane spanning tree in a complete geometric graph. For this problem, we present an approximation algorithm with ratio 0.503; this is an extension of the algorithm presented by Dumitrescu and Tóth (Discrete Comput Geom 44(4):727–752,
2010
) whose ratio is 0.502.
For points that are in convex position, the maximum bichromatic plane spanning tree problem can be solved in
O
(
n
3
)
time. We present an
O
(
n
5
)
-time algorithm that solves this problem for the case where the red points lie on a line and the blue points lie on one side of the line. |
|---|---|
| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 |
| ISSN: | 0178-4617 1432-0541 |
| DOI: | 10.1007/s00453-018-0482-x |