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Abstract We prove character ratio bounds for finite exceptional groups $G(q)$ of Lie type. These take the form $$\dfrac{|\chi (g)|}{\chi (1)} \le \dfrac{c}{q^k}$$ for all nontrivial irreducible characters $$\chi$$ and nonidentity elements $$g$$, where $$c$$ is an absolute constant, and $$k$$ is a positive integer. Applications are given to bounding mixing times for random walks on these groups and also diameters of their McKay graphs. 

Abstract For every integer k there exists a bound $$B=B(k)$$ B = B ( k ) such that if the characteristic polynomial of $$g\in \textrm{SL}_n(q)$$ g ∈ SL n ( q ) is the product of $$\le k$$ ≤ k pairwise distinct monic irreducible polynomials over $$\mathbb {F}_q$$ F q , then every element x of $$\textrm{SL}_n(q)$$ SL n ( q ) of support at least B is the product of two conjugates of g . We prove this and analogous results for the other classical groups over finite fields; in the orthogonal and symplectic cases, the result is slightly weaker. With finitely many exceptions ( p ,  q ), in the special case that $$n=p$$ n = p is prime, if g has order $$\frac{q^p-1}{q-1}$$ q p - 1 q - 1 , then every non-scalar element $$x \in \textrm{SL}_p(q)$$ x ∈ SL p ( q ) is the product of two conjugates of g . The proofs use the Frobenius formula together with upper bounds for values of unipotent and quadratic unipotent characters in finite classical groups. 

Abstract We prove that any element in a sufficiently large transitive finite simple permutation group is a product of two derangements.