A variety of partially conservative sentences

Abstract

We study the existence of a $\Theta$ sentence which is simultaneously $\Gamma$-conservative over consistent RE extensions $T$ and $U$ of Peano Arithmetic for various reasonable pairs $(\Gamma ,\Theta )$. As a result of this study, we prove the existence of a sentence which is essentially $\Theta$ and exactly hereditarily $\Gamma$-conservative over any single theory $T$ for various reasonable pairs $(\Gamma ,\Theta )$. This is an affirmative answer to Guaspari's question.

41 pages