No CrossRef data available.
Published online by Cambridge University Press: 28 April 2023
${\mathsf {CAC\ for\ trees}}$ is the statement asserting that any infinite subtree of
$\mathbb {N}^{<\mathbb {N}}$ has an infinite path or an infinite antichain. In this paper, we study the computational strength of this theorem from a reverse mathematical viewpoint. We prove that
${\mathsf {CAC\ for\ trees}}$ is robust, that is, there exist several characterizations, some of which already appear in the literature, namely, the statement
$\mathsf {SHER}$ introduced by Dorais et al. [8], and the statement
$\mathsf {TAC}+\mathsf {B}\Sigma ^0_2$ where
$\mathsf {TAC}$ is the tree antichain theorem introduced by Conidis [6]. We show that
${\mathsf {CAC\ for\ trees}}$ is computationally very weak, in that it admits probabilistic solutions.