Let H(n,q2) be a non–degenerate Hermitian variety of PG(n,q2), n≥2. Let NU(n+1,q2) be the graph whose vertices are the points of PG(n,q2)∖H(n,q2) and two vertices P1,P2 are adjacent if the line joining P1 and P2 is tangent to H(n,q2). Then NU(n+1,q2) is a strongly regular graph. In this paper we show that NU(n+1,q2), n≠3, is not determined by its spectrum.
Graphs cospectral with NU(n + 1,q2), n ≠ 3 / Ihringer, F.; Pavese, F.; Smaldore, V.. - In: DISCRETE MATHEMATICS. - ISSN 0012-365X. - 344:11(2021), p. 112560.112560. [10.1016/j.disc.2021.112560]
Graphs cospectral with NU(n + 1,q2), n ≠ 3
Pavese F.
;
2021-01-01
Abstract
Let H(n,q2) be a non–degenerate Hermitian variety of PG(n,q2), n≥2. Let NU(n+1,q2) be the graph whose vertices are the points of PG(n,q2)∖H(n,q2) and two vertices P1,P2 are adjacent if the line joining P1 and P2 is tangent to H(n,q2). Then NU(n+1,q2) is a strongly regular graph. In this paper we show that NU(n+1,q2), n≠3, is not determined by its spectrum.File in questo prodotto:
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