On the Cantor–Bendixson rank of a set that is searchable in Gödel’s T
Dag Normann · Computability · 2016
We prove that if a closed subset X of the Baire space is searchable in the sense of Escardó [Logical Methods in Computer Science 4 (3) (2008), 3], and by a functional definable in Gödel’s T , then X is countable, and the Cantor–Bendixson rank of X is