Finite-state dimension and real arithmetic

  • Authors:
  • David Doty;Jack H. Lutz;Satyadev Nandakumar

  • Affiliations:
  • Department of Computer Science, Iowa State University, Ames, IA 50011, USA;Department of Computer Science, Iowa State University, Ames, IA 50011, USA;Department of Computer Science, Iowa State University, Ames, IA 50011, USA

  • Venue:
  • Information and Computation
  • Year:
  • 2007

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Abstract

We use entropy rates and Schur concavity to prove that, for every integer k=2, every nonzero rational number q, and every real number @a, the base-k expansions of @a, q+@a, and q@a all have the same finite-state dimension and the same finite-state strong dimension. This extends, and gives a new proof of, Wall's 1949 theorem stating that the sum or product of a nonzero rational number and a Borel normal number is always Borel normal.