TY - GEN

T1 - Flip distances between graph orientations

AU - Aichholzer, Oswin

AU - Cardinal, Jean

AU - Huynh, Tony

AU - Knauer, Kolja

AU - Mütze, Torsten

AU - Steiner, Raphael

AU - Vogtenhuber, Birgit

PY - 2019

Y1 - 2019

N2 - Flip graphs are a ubiquitous class of graphs, which encode relations induced on a set of combinatorial objects by elementary, local changes. A natural computational problem to consider is the flip distance: Given two objects, what is the minimum number of flips needed to transform one into the other? We consider flip graphs on so-called $-orientations of a graph $G$, in which every vertex $v$ has a specified outdegree $v)$, and a flip consists of reversing all edges of a directed cycle. We prove that deciding whether the flip distance between two $-orientations of a planar graph $G$ is at most 2 is complete. This also holds in the special case of plane perfect matchings, where flips involve alternating cycles. We also consider the dual question of the flip distance between graph orientations in which every cycle has a specified number of forward edges, and a flip is the reversal of all edges in a minimal directed cut. In general, the problem remains hard, but if we only change sinks into sources, or vice-versa, then the problem can be solved in polynomial time.

AB - Flip graphs are a ubiquitous class of graphs, which encode relations induced on a set of combinatorial objects by elementary, local changes. A natural computational problem to consider is the flip distance: Given two objects, what is the minimum number of flips needed to transform one into the other? We consider flip graphs on so-called $-orientations of a graph $G$, in which every vertex $v$ has a specified outdegree $v)$, and a flip consists of reversing all edges of a directed cycle. We prove that deciding whether the flip distance between two $-orientations of a planar graph $G$ is at most 2 is complete. This also holds in the special case of plane perfect matchings, where flips involve alternating cycles. We also consider the dual question of the flip distance between graph orientations in which every cycle has a specified number of forward edges, and a flip is the reversal of all edges in a minimal directed cut. In general, the problem remains hard, but if we only change sinks into sources, or vice-versa, then the problem can be solved in polynomial time.

M3 - Conference contribution

VL - 11789

T3 - Lecture Notes in Computer Science (LNCS)

SP - 120

EP - 134

BT - 45th International Workshop on Graph-Theoretic Concepts in Computer Science

CY - Vall de Nuria, Spain

ER -