Polylog depth, highness and lowness for E

Abstract

We study the relations between the notions of highness, lowness and logical depth in the setting of complexity theory. We introduce a new notion of polylog depth based on time bounded Kolmogorov complexity. We show polylog depth satisfies all basic logical depth properties, namely sets in P are not polylog deep, sets with (time bounded)-Kolmogorov complexity greater than polylog are not polylog deep, and only polylog deep sets can polynomially Turing compute a polylog deep set. We prove that if NP does not have p-measure zero, then NP contains polylog deep sets. We show that every high set for E contains a polylog deep set in its polynomial Turing degree, and that there exist Low(E,EXP) polylog deep sets. Keywords: algorithmic information theory; Kolmogorov complexity; Bennett logical depth.