Controlling The Skips of Arithmetic Sets

Abstract

Andrews, Ganchev, Kuyper, Lempp, Miller, A.\ Soskova, and M.\ Soskova conjectured that skip-cototality coincides with weak cototality. We show that the conjecture is false by constructing a $Π^0_2$ set whose skip does not have a cototal degree. We further adapt this construction to obtain additional results. We prove that for each odd $n$, there is a $Π^0_{n+1}$ degree whose $n$-iterated skip does not have a cototal degree. We show that there is a $Π^0_2$ degree which does not contain an introenumerable set.