Title
Integer realizations of disk and segment graphs
Abstract
A disk graph is the intersection graph of disks in the plane, a unit disk graph is the intersection graph of same radius disks in the plane, and a segment graph is an intersection graph of line segments in the plane. Every disk graph can be realized by disks with centers on the integer grid and with integer radii; and similarly every unit disk graph can be realized by disks with centers on the integer grid and equal (integer) radius; and every segment graph can be realized by segments whose endpoints lie on the integer grid. Here we show that there exist disk graphs on n vertices such that in every realization by integer disks at least one coordinate or radius is 2^2^^^@W^^^(^^^n^^^) and on the other hand every disk graph can be realized by disks with integer coordinates and radii that are at most 2^2^^^O^^^(^^^n^^^); and we show the analogous results for unit disk graphs and segment graphs. For (unit) disk graphs this answers a question of Spinrad, and for segment graphs this improves over a previous result by Kratochvil and Matousek.
Year
DOI
Venue
2011
10.1016/j.jctb.2012.09.004
Journal of Combinatorial Theory
Keywords
DocType
Volume
integer realization,unit disk graph,integer grid,disk graph,analogous result,integer disk,integer radius,line segment,segment graph,radius disk,intersection graph
Journal
103
Issue
ISSN
Citations 
1
0095-8956
9
PageRank 
References 
Authors
0.53
25
2
Name
Order
Citations
PageRank
Colin McDiarmid11071167.05
Tobias Müller221415.95