Structural Properties of Shortest Flip Sequences Between Plane Spanning Trees

Fuente: arXiv
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Auteurs principaux: Aichholzer, Oswin, Dorfer, Joseph, Kramer, Peter, Rieck, Christian, Vogtenhuber, Birgit
Format: Preprint
Publié: 2026
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author Aichholzer, Oswin
Dorfer, Joseph
Kramer, Peter
Rieck, Christian
Vogtenhuber, Birgit
author_facet Aichholzer, Oswin
Dorfer, Joseph
Kramer, Peter
Rieck, Christian
Vogtenhuber, Birgit
contents We study the reconfiguration of plane spanning trees on point sets in the plane in convex position, where a reconfiguration step (flip) replaces one edge with another, yielding again a plane spanning tree. The flip distance between two trees is then the minimum number of flips needed to transform one tree into the other. We study structural properties of shortest flip sequences. The folklore happy edge conjecture suggests that any edge shared by both the initial and target tree is never flipped in a shortest flip sequence. The more recent parking edge conjecture, which would have implied the happy edge conjecture, states that there exist shortest flip sequences which use only edges of the start and target tree, and edges in the convex hull of the point set. Finally, another conjecture that is implicit in the literature is the reparking conjecture which states that no edge is flipped more than twice. Essentially all recent flip algorithms respect these three conjectures and the properties they imply. We study cases in which the latter two conjectures hold and disprove them for the general setting. (Shortened abstract due to arXiv restrictions.)
format Preprint
id arxiv_https___arxiv_org_abs_2603_05205
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Structural Properties of Shortest Flip Sequences Between Plane Spanning Trees
Aichholzer, Oswin
Dorfer, Joseph
Kramer, Peter
Rieck, Christian
Vogtenhuber, Birgit
Computational Geometry
Discrete Mathematics
We study the reconfiguration of plane spanning trees on point sets in the plane in convex position, where a reconfiguration step (flip) replaces one edge with another, yielding again a plane spanning tree. The flip distance between two trees is then the minimum number of flips needed to transform one tree into the other. We study structural properties of shortest flip sequences. The folklore happy edge conjecture suggests that any edge shared by both the initial and target tree is never flipped in a shortest flip sequence. The more recent parking edge conjecture, which would have implied the happy edge conjecture, states that there exist shortest flip sequences which use only edges of the start and target tree, and edges in the convex hull of the point set. Finally, another conjecture that is implicit in the literature is the reparking conjecture which states that no edge is flipped more than twice. Essentially all recent flip algorithms respect these three conjectures and the properties they imply. We study cases in which the latter two conjectures hold and disprove them for the general setting. (Shortened abstract due to arXiv restrictions.)
title Structural Properties of Shortest Flip Sequences Between Plane Spanning Trees
topic Computational Geometry
Discrete Mathematics
url https://arxiv.org/abs/2603.05205