A graph is terminal ∆ − Y -reducible if, it can be reduced to a distinguished set of terminal vertices by a sequence of series-parallel reductions and ∆−Y -transformations...
Based on an inductive definition of triangulations, a theory of undirected planar graphs is developed in Isabelle/HOL. The proof of the 5 colour theorem is discussed in some detai...
A graph with an ordered k-partition of the vertices is radial level planar if there is a strictly outward drawing on k concentric levels without crossings. Radial level planarity ...
Christian Bachmaier, Franz-Josef Brandenburg, Mich...
We show how to utilize the cactus representation of all minimum cuts of a graph to visualize the minimum cuts of a planar graph in a planar drawing. In a first approach the cactus...
Ulrik Brandes, Sabine Cornelsen, Christian Fie&szl...