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circular coloring
Circular colouring the orthogonality graph ★★
Author(s): DeVos; Ghebleh; Goddyn; Mohar; Naserasr
Let denote the graph with vertex set consisting of all lines through the origin in
and two vertices adjacent in
if they are perpendicular.
Problem Is
?
![$ \chi_c({\mathcal O}) = 4 $](/files/tex/ee0ecd597af84da66753671f734858c77288d4be.png)
Keywords: circular coloring; geometric graph; orthogonality
Circular coloring triangle-free subcubic planar graphs ★★
Problem Does every triangle-free planar graph of maximum degree three have circular chromatic number at most
?
![$ \frac{20}{7} $](/files/tex/bad459acf1e14f972d8bf6c9f92912e0be945739.png)
Keywords: circular coloring; planar graph; triangle free
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