Thin set theorem for arbitrarily many colors implies bounding

Abstract

The thin set theorem $\mathsf{RT}_{<\infty,\ell}^{n}$ asserts that for every natural number $k$, each coloring $c\colon[\mathbb{N}]^n \to \{0,1,\dots,k-1\}$ admits an infinite set $H$ such that $|c([H]^n)| \le \ell$. Within the framework of the reverse mathematics of second-order arithmetic, $\mathsf{RT}_{<\infty,\ell}^{n}$ implies the $\Sigma_{n+1}^{0}$-bounding principle ($\mathsf{B}\Sigma_{n+1}^{0}$) over $\mathsf{RCA}_0$ for all natural numbers $n, \ell \ge 1$.