Space Bounded Computations: Review And New Separation Results

In this paper we review the key results about space bounded complexity classes, discuss the central open problems and outline the prominent proof techniques. We show that, for a slightly modified Turing machine model, low level deterministic and nondeterministic space bounded complexity classes are different. Furthermore, for this computation model, we show that Savitch’s theorem and the Immerman-Szelepcs´enyi theorem do not hold in the range lg lg n to lg n. We also present other changes in the computation model which bring out and clarify the importance of space constructibility. We conclude by enumerating open problems which arise out of the discussion.

• Type: Conference
• Year: 1989
• Where: MFCS
• Authors: Juris Hartmanis, Desh Ranjan
• Keywords: Complexity Classes, Computation Model, MFCS 1989, Space Bounded Complexity, Theoretical Computer Science