Contractable 2-connected subgraphs in minimally 3-connected graphs
Abstract
We study the 2-connected subgraphs of minimally 3-connected graphs whose contraction preserves 3-connectedness. We show that every minimally 3-connected graph that is not a wheel or a complete bipartite graph K3,n contains a contractable 2-connected induced subgraph that is a cycle, a fan, a K2,n or a K3,n. In addition, these subgraphs satisfy certain degree restrictions. We show that none of these four families can be discarded since for each one of the four families, there exists a minimally 3-connected graph containing a contractable induced 2-connected subgraph in that family and none in the other three families. Reversing the contraction process gives a new construction for 3-connected graphs using edge addition, expansions into prescribed 2-connected subgraphs and Y-sum.
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BibTeX
@misc{tao2026contractable,
title = {{Contractable 2-connected subgraphs in minimally 3-connected graphs}},
author = {Rongchuan Tao},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.01588},
eprint = {2611.01588},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.01588},
}
RIS
TY - UNPB
TI - Contractable 2-connected subgraphs in minimally 3-connected graphs
AU - Rongchuan Tao
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.01588
UR - https://arxiv.org/abs/2611.01588
AB - We study the 2-connected subgraphs of minimally 3-connected graphs whose contraction preserves 3-connectedness. We show that every minimally 3-connected graph that is not a wheel or a complete bipartite graph K_3,n contains a contractable 2-connected induced subgraph that is a cycle, a fan, a K_2,n or a K_3,n. In addition, these subgraphs satisfy certain degree restrictions. We show that none of these four families can be discarded since for each one of the four families, there exists a minimally 3-connected graph containing a contractable induced 2-connected subgraph in that family and none in the other three families. Reversing the contraction process gives a new construction for 3-connected graphs using edge addition, expansions into prescribed 2-connected subgraphs and Y-sum.
ER -