![](/files/happy5.png)
Naserasr, Reza
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
![Syndicate content Syndicate content](/misc/feed.png)