Let Lϕ,λ = {ω ∈ Σ∗ | ϕ(ω) > λ} be the language recognized by a formal series ϕ:Σ∗ → ℝ with isolated cut point λ. We provide new conditions that guarantee the regularity of the language Lϕ,λ in the case that ϕ is rational or ϕ is a Hadamard quotient of rational series. Moreover the decidability property of such conditions is investigated.

We prove that a word of length n from a finitely ambiguous context-free language can be generated at random under uniform distribution in O(n2 log n) time by a probabilistic random access machine assuming a logarithmic cost criterion. We also show that the same problem can be solved in polynomial time for every language accepted by a polynomial time 1-NAuxPDA with polynomially bounded ambiguity.