Kranjc, Jaka; Lužar, Borut; Mockovčiaková, Martina; … - In: Journal of Global Optimization 60 (2014) 4, pp. 793-799
The coloring of disk graphs is motivated by the frequency assignment problem. In 1998, Malesińska et al. introduced double disk graphs as their generalization. They showed that the chromatic number of a double disk graph <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$$G$$</EquationSource> <EquationSource Format="MATHML"> <math xmlns:xlink="http://www.w3.org/1999/xlink"> <mi>G</mi> </math> </EquationSource> </InlineEquation> is at most <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$$33\,\omega (G) - 35$$</EquationSource> <EquationSource Format="MATHML"> <math xmlns:xlink="http://www.w3.org/1999/xlink"> <mrow> <mn>33</mn> <mspace width="0.166667em"/> <mi mathvariant="italic">ω</mi> <mo stretchy="false">(</mo> <mi>G</mi> <mo stretchy="false">)</mo> <mo>-</mo> <mn>35</mn> </mrow> </math> </EquationSource>...</equationsource></equationsource></inlineequation></equationsource></equationsource></inlineequation>