Elementary differences between the (2p)-C. E. and the (2p + 1)-C. E. enumeration degrees

Abstract

It is proved that the (2p)-c. e. e-degrees are not elementarily equivalent to the (2p + 1)-c. e. e-degrees for each nonzero p ∈ ω. It follows that m-c. e. e-degrees are not elementarily equivalent to the n-c. e. e-degrees if 1 < m < n. © 2007, Association for Symbolic Logic.