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Nut Graph


NutGraphs

A nut graph is a graph on n>=2 vertices with adjacency matrix A such that A has matrix rank 1 and contains no 0 element (Sciriha 1998, 2008; Sciriha and Gutman, 1998; and Sciriha and Fowler 2008). The numbers of nut graphs on n=1, 2, ... vertices are 0, 0, 0, 0, 0, 0, 3, 13, 560, 12551, 2060490, 208147869, 96477266994, ... (House of Graphs).

n-antiprism graphs are nut graphs when n is not divisible by 3.

NutCirculantGraphs

Damnjanovi'c (2022) proved that a circulant nut graph with vertex count n and vertex degree d exists for the following values and no others:

1. n even, d=8 (mod 4), and n>=d+4,

2. n=14 and d=8,

3. n>=18 even and d=8,

4. n even, d=8, and n>=14, or

5. n even, d>=16, and n>=d+6. The complete set of circulant nut graphs on 16 or fewer vertices are illustrated above.


See also

Adjacency Matrix, Null Space, Matrix Rank

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References

Coolsaet, K.; Fowler, P. W.; And Goedgebeur, J. "Generation and Properties of Nut Graphs." MATCH Commun. Math. Comput. Chem. 80, 423-444, 2018.Damnjanovi'c, I. "Complete Resolution of the Circulant Nut Graph Order-Degree Existence Problem." 6 Dec 2022. https://arxiv.org/abs/2212.03026.Gauci, J. B.; Pisanski, T.; And Sciriha, I. "Existence of Regular Nut Graphs and the Fowler Construction." 12 Nov 2019. https://arxiv.org/abs/1904.02229.Fowler, P. W.; Gauci, J. B.; Goedgebeur, J.; Pisanski, T.; and Sciriha, I. "Existence of Regular Nut Graphs for Degree at Most 11." Disc. Math. Graph Th. 40, 533-557, 2020.House of Graphs. "Nut Graphs." https://hog.grinvin.org/meta-directory/nut.Sciriha. I. "On the Construction of Graphs of Nullity One." Disc. Math. 181, 193-211, 1998.Sciriha, I. "Coalesced and Embedded Nut Graphs in Singular Graphs." Ars Math. Contemp. 1, 20-31, 2008.Sciriha, I. and Fowler, P. W. "On Nut and Core Singular Fullerenes." Disc. Math. 308, 267-276, 2008.Sciriha, I. and Gutman, I. "Nut Graphs: Maximally Extending Cores." Util. Math. 54, 257-272, 1998.

Cite this as:

Weisstein, Eric W. "Nut Graph." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/NutGraph.html

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