Armin Hemmerling | Searcharxiv

arXiv2013

On the Tape-Number Problem for Deterministic Time Classes

For any time bound f, let H(f) denote the hierarchy conjecture which means that the restriction of the numbers of work tapes of deterministic Turing machines to some b generates an infinite hierarchy of proper subclasses DTIME_b(f) \subset \DTIME(f). We show that H(f) implies separations of deterministic from nondeterministic time classes. H(f) follows from the gap property, G(f), which says that there is a time-constructible bound f_2 such that f \in o(f_2) and DTIME(f)=DTIME(f_2). G(f) implies further separations. All these relationships relativize.

cs.CC↗

arXiv2013

On Regular Sets of Bounds and Determinism versus Nondeterminism

This paper illustrates the richness of the concept of regular sets of time bounds and demonstrates its application to problems of computational complexity. There is a universe of bounds whose regular subsets allow to represent several time complexity classes of common interest and are linearly ordered with respect to the confinality relation which implies the inclusion between the corresponding complexity classes. By means of classical results of complexity theory, the separation of determinism from nondeterminism is possible for a variety of sets of bounds below $n\cdot\log^*(n)$. The system of all regular bound sets ordered by confinality allows the order-isomorphic embedding of, e.g., the ordered set of real numbers or the Cantor discontinuum.

cs.CC↗