Abstract:
Finite groups are isospectral if they have the same sets of element orders. We complete the description of the finite groups isospectral to the simple groups $U_5(q)$, $L_6(q)$, and $U_6(q)$, with $q$ odd. We also prove that the exceptional groups of Lie type do not occur among the composition factors of finite groups isospectral to simple classical groups.
Keywords:simple classical group, element order, recognition by spectrum.