A note on the diamond operator
Linda Brown Westrick · Computability · 2020
We show that if [Formula: see text] and [Formula: see text], then [Formula: see text], where ⋆ and ◇ are the following operations in the Weihrauch lattice: ⋆ is the compositional product, which allows the use of two principles in sequence, while the diamond operator ◇ allows an arbitrary but finite number of uses of the given principle in sequence. This answers a question of Pauly.