We prove the result stated in the title. Furthermore, it is proved that for any > 0, there is a 1-tough chordal planar graph G such that the length of a longest cycle of G is less than |V (G )|.
On certain Hamiltonian cycles in planar graphs
✍ Scribed by B�hme, T.; Harant, J.; Tk�?, M.
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 162 KB
- Volume
- 32
- Category
- Article
- ISSN
- 0364-9024
No coin nor oath required. For personal study only.
✦ Synopsis
The problem is considered under which conditions a 4-connected planar or projective planar graph has a Hamiltonian cycle containing certain prescribed edges and missing certain forbidden edges. The results are applied to obtain novel lower bounds on the number of distinct Hamiltonian cycles that must be present in a 5-connected graph that is embedded into the plane or into the projective plane with face-width at least five. Especially, we show that every 5-connected plane or projective plane triangulation on n vertices with no non-contractible cyles of length less than five contains at least 2 O(n 1/4 ) distinct Hamiltonian cycles.
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