4 research outputs found
On Colourability of Polygon Visibility Graphs
We study the problem of colouring the visibility graphs of polygons. In particular, we provide
a polynomial algorithm for 4-colouring of the polygon visibility graphs, and prove that the 6-
colourability question is already NP-complete for them
Coloring polygon visibility graphs and their generalizations
Curve pseudo-visibility graphs generalize polygon and pseudo-
polygon visibility graphs and form a hereditary class of
graphs. We prove that every curve pseudo-visibility graph
with clique number ω has chromatic number at most 3 · 4ω−1.
The proof is carried through in the setting of ordered graphs;
we identify two conditions satisfied by every curve pseudo-
visibility graph (considered as an ordered graph) and prove
that they are sufficient for the claimed bound. The proof is
algorithmic: both the clique number and a coloring with the
claimed number of colors can be computed in polynomial time