The spectral radius of graphs with no K2,t minor.

Let t ≥ 3 and G be a graph of order n , with no K 2 , t minor. If n > 400 t 6 , then the spectral radius μ ( G ) satisfies μ ( G ) ≤ t − 1 2 + n + t 2 − 2 t − 3 4 , with equality if and only if n ≡ 1 ( mod t ) and G = K 1 ∨ ⌊ n / t ⌋ K t . For t = 3 the maximum μ ( G ) is found exactly for any n > 40000 . [ABSTRACT FROM AUTHOR]