Chicago Journal of Theoretical Computer Science

CJTCS Special Issue: CATS 2010

Selected papers from

2010 Computing: The Australasian Theory Symposium

held in Brisbane, Australia, January 18-21 2010.

Guest Editors: Taso Viglas, University of Sydney, Australia

Alex Potanin, Victoria University, Wellington, NZ

Article 2011-4

Published by the Department of Computer Science, The University of Chicago.


Notes on Large Angle Crossing Graphs

Vida Dujmovic
Computational Geometry Lab
School of Computer Science
Carleton University
vida [at] cs [dot] mcgill [dot] ca,
Joachim Gudmundsson
NICTA
Sydney
Australia
joachim.gudmundsson [at] gmail [dot] com,
Pat Morin
Computational Geometry Lab
School of Computer Science
Carleton University
morin [at] scs [dot] carleton [dot] ca,
and
Thomas Wolle
NICTA
Sydney
Australia
thomas.wolle [at] gmail [dot] com
May 6, 2011
Abstract

A geometric graph G is an a angle crossing (alpha AC) graph if every pair of crossing edges in G cross at an angle of at least alpha. The concept of right angle crossing (RAC) graphs alpha = pi/2) was recently introduced by Didimo et al. [10]. It was shown that any RAC graph with n vertices has at most 4n-10 edges and that there are infinitely many values of n for which there exists a RAC graph with n vertices and 4n-10 edges. In this paper, we give upper and lower bounds for the number of edges in alphaAC graphs for all 0 < alpha < pi/2.



DOI: 10.4086/cjtcs.2011.004


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