Outer 1-Planar Graphs
A graph is outer 1-planar ( o1p ) if it can be drawn in the plane such that all vertices are in the outer face and each edge is crossed at most once. o1p graphs generalize outerplanar graphs, which can be recognized in linear time, and specialize 1-planar graphs, whose recognition is N P -hard. We e...
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| Veröffentlicht in: | Algorithmica Jg. 74; H. 4; S. 1293 - 1320 |
|---|---|
| Hauptverfasser: | , , , , , , |
| Format: | Journal Article |
| Sprache: | Englisch |
| Veröffentlicht: |
New York
Springer US
01.04.2016
Springer Nature B.V |
| Schlagworte: | |
| ISSN: | 0178-4617, 1432-0541 |
| Online-Zugang: | Volltext |
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| Zusammenfassung: | A graph is outer 1-planar (
o1p
) if it can be drawn in the plane such that all vertices are in the outer face and each edge is crossed at most once.
o1p
graphs generalize outerplanar graphs, which can be recognized in linear time, and specialize 1-planar graphs, whose recognition is
N
P
-hard. We explore
o1p
graphs. Our first main result is a linear-time algorithm that takes a graph as input and returns a positive or a negative witness for
o1p
. If a graph
G
is
o1p
, then the algorithm computes an embedding and can augment
G
to a maximal
o1p
graph. Otherwise,
G
includes one of six minors, which is detected by the recognition algorithm. Secondly, we establish structural properties of
o1p
graphs.
o1p
graphs are planar and are subgraphs of planar graphs with a Hamiltonian cycle. They are neither closed under edge contraction nor under subdivision. Several important graph parameters, such as treewidth, colorability, stack number, and queue number, increase by one from outerplanar to
o1p
graphs. Every
o1p
graph of size
n
has at most
5
2
n
-
4
edges and there are maximal
o1p
graphs with
11
5
n
-
18
5
edges, and these bounds are tight. Finally, every
o1p
graph has a straight-line grid drawing in
O
(
n
2
)
area with all vertices in the outer face, a planar visibility representation in
O
(
n
log
n
)
area, and a 3D straight-line drawing in linear volume, and these drawings can be constructed in linear time. |
|---|---|
| Bibliographie: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 14 |
| ISSN: | 0178-4617 1432-0541 |
| DOI: | 10.1007/s00453-015-0002-1 |