Planar acyclic oriented graphs
β Scribed by Carsten Thomassen
- Book ID
- 104736454
- Publisher
- Springer Netherlands
- Year
- 1989
- Tongue
- English
- Weight
- 725 KB
- Volume
- 5
- Category
- Article
- ISSN
- 0167-8094
No coin nor oath required. For personal study only.
β¦ Synopsis
A plane Hasse representation of an acyclic oriented graph is a drawing of the graph in the Euchdean plane such that all arcs are straight-line segments directed upwards and such that no two arcs cross. We characterize completely those oriented graphs which have a plane Hasse representation such that all faces are bounded by convex polygons. From this we derive the Hasse representation analogue, due to Kelly and Rival of Fary's theorem on straight-line representations of planar graphs and the Kuratowski type theorem of Platt for acyclic oriented graphs with only one source and one sink. Finally, we describe completely those acyclic oriented graphs which have a vertex dominating all other vertices and which have no plane Hasse representation, a problem posed by Trotter.
π SIMILAR VOLUMES
## Let G be a finite graph with p vertices and x its chromatic polynomial. A combinatorial interpretation is given to the positive integer (-l)px(-A), where h is a positive integer, in terms of acyclic orientations of G. In particular, (-l)Px(-1) is the number of acyclic orientations of G. An appl
It is &own that every rnzknal plsnar graph Itriangulakn) can be contracted at an arbitrary point (by identifying it with an adjacent point) c,o that triangularity is preserved. This is used as B lemma to prove that every triangulation con be (a) oriented so that with threg: exceptions every point hs