On closure properties of Hash P in the context of PF (omicron) Hash P
Mitsunori Ogiwara, Thomas Thierauf, Seinosuke Toda, Osamu Watanabe · 2002
It is shown that while absolute answers to open questions about relationships between counting classes seem hard to get, it is still possible to obtain relative answers that help us to develop intuition about or understanding of these relationships. In particular, a structural approach to extending such understanding is proposed.>