Constructive Dimension and Weak Truth-Table Degrees

  • Authors:
  • Laurent Bienvenu;David Doty;Frank Stephan

  • Affiliations:
  • Laboratoire d'Informatique Fondamentale de Marseille, Université de Provence, 39 rue Joliot-Curie, 13453 Marseille Cedex 13, France;Department of Computer Science, Iowa State University, Ames, IA 50011, USA;School of Computing and Department of Mathematics, National University of Singapore, 2 Science Drive 2, Singapore 117543, Republic of Singapore

  • Venue:
  • CiE '07 Proceedings of the 3rd conference on Computability in Europe: Computation and Logic in the Real World
  • Year:
  • 2007

Quantified Score

Hi-index 0.00

Visualization

Abstract

This paper examines the constructive Hausdorff and packingdimensions of weak truth-table degrees. The main result is thatevery infinite sequence Swith constructive Hausdorffdimension dimH(S) and constructive packingdimension dimP(S) is weak truth-tableequivalent to a sequence Rwith ${\rm dim_H}({\it R}) \geq{\rm dim_H}(S) / {\rm dim_P}(S) - \epsilon$, for arbitraryε 0. Furthermore, ifdimP(S) 0, thendimP(R) ≥ 1 - ε. Thereduction thus serves as a randomness extractorthatincreases the algorithmic randomness of S, as measured byconstructive dimension.A number of applications of this result shed new light on theconstructive dimensions of wtt degrees (and, by extension, Turingdegrees). A lower bound of dimH(S) /dimP(S) is shown to hold for the wtt degree ofany sequence S. A new proof is given of a previously-knownzero-one law for the constructive packing dimension of wtt degrees.It is also shown that, for any regularsequence S(that is, dimH(S) =dimP(S)) such that dimH(S) 0, the wtt degree of Shas constructive Hausdorff andpacking dimension equal to 1.Finally, it is shown that no single Turing reduction can be auniversalconstructive Hausdorff dimension extractor.