A construction of a $\frac{3}{2}$-tough plane triangulation with no 2-factor
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arXiv
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| Format: | Preprint |
| Publié: |
2022
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| _version_ | 1866929328925704192 |
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| author | Shan, Songling |
| author_facet | Shan, Songling |
| contents | In 1956, Tutte proved the celebrated theorem that every 4-connected planar graph is hamiltonian. This result implies that every more than $\frac{3}{2}$-tough planar graph on at least three vertices is hamiltonian and so has a 2-factor. Owens in 1999 constructed non-hamiltonian maximal planar graphs of toughness arbitrarily close to $\frac{3}{2}$ and asked whether there exists a maximal non-hamiltonian planar graph of toughness exactly $\frac{3}{2}$. In fact, the graphs Owens constructed do not even contain a 2-factor. Thus the toughness of exactly $\frac{3}{2}$ is the only case left in asking the existence of 2-factors in tough planar graphs. This question was also asked by Bauer, Broersma, and Schmeichel in a survey. In this paper, we close this gap by constructing a maximal $\frac{3}{2}$-tough plane graph with no 2-factor, answering the question asked by Owens as well as by Bauer, Broersma, and Schmeichel. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2211_11714 |
| institution | arXiv |
| publishDate | 2022 |
| record_format | arxiv |
| spellingShingle | A construction of a $\frac{3}{2}$-tough plane triangulation with no 2-factor Shan, Songling Combinatorics In 1956, Tutte proved the celebrated theorem that every 4-connected planar graph is hamiltonian. This result implies that every more than $\frac{3}{2}$-tough planar graph on at least three vertices is hamiltonian and so has a 2-factor. Owens in 1999 constructed non-hamiltonian maximal planar graphs of toughness arbitrarily close to $\frac{3}{2}$ and asked whether there exists a maximal non-hamiltonian planar graph of toughness exactly $\frac{3}{2}$. In fact, the graphs Owens constructed do not even contain a 2-factor. Thus the toughness of exactly $\frac{3}{2}$ is the only case left in asking the existence of 2-factors in tough planar graphs. This question was also asked by Bauer, Broersma, and Schmeichel in a survey. In this paper, we close this gap by constructing a maximal $\frac{3}{2}$-tough plane graph with no 2-factor, answering the question asked by Owens as well as by Bauer, Broersma, and Schmeichel. |
| title | A construction of a $\frac{3}{2}$-tough plane triangulation with no 2-factor |
| topic | Combinatorics |
| url | https://arxiv.org/abs/2211.11714 |