The derivational complexity of string rewriting systems

  • Authors:
  • Yuji Kobayashi

  • Affiliations:
  • -

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2012

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Abstract

We study the derivational complexities of string rewriting systems. We discuss the following fundamental question: which functions can be derivational complexities of terminating finite string rewriting systems? They are recursive, but for any recursive function, there is a derivational complexity larger than it. We relate them to the time functions of Turing machines. In particular, we show that the functions n^@a(@a2) and @a^n(@a1) for a real number @a are equivalent to the derivational complexity of some finite string rewriting systems if the computational complexity of @a is relatively low (for example, @a is rational, algebraic, @p or e). On the other hand, they cannot be equivalent to any derivational complexities if the complexity of @a is high.