EN
We prove that if the topology on the set Seq of all finite sequences of natural numbers is determined by $P_λ$-filters and λ ≤ 𝔟, then Seq is a $P_λ$-set in its Čech-Stone compactification. This improves some results of Simon and of Juhász and Szymański. As a corollary we obtain a generalization of a result of Burke concerning skeletal maps and we partially answer a question of his.