Gap sets for the spectra of cubic graphs
We study gaps in the spectra of the adjacency matrices of large finite cubic graphs. It is known that the gap intervals ( 2 2 , 3 ) (2 \sqrt {2},3) and [ − 3 , − 2 ) [-3,-2) achieved in cubic Ramanujan graphs and line graphs are maximal. We give constraints on spectra in [ − 3 , 3 ] [-3,3] which are maximally gapped and construct examples which achieve these bounds. These graphs yield new instances of maximally gapped intervals. We also show that every point in [ − 3 , 3 ) [-3,3) can be gapped by planar cubic graphs. Our results show that the study of spectra of cubic, and even planar cubic, graphs is subtle and very rich.
2008 ◽
Vol 308
(12)
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pp. 2351-2365
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2015 ◽
Vol 52
(5)
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pp. 1423-1431
Keyword(s):
2014 ◽
Vol 26
(2)
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pp. 81-91
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Keyword(s):
2000 ◽
Vol 93
(supplement_3)
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pp. 120-127
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Keyword(s):
2000 ◽
Vol 93
(supplement_3)
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pp. 113-119
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2000 ◽
Vol 93
(supplement_3)
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pp. 96-101
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