Bounds for the element distinctness problem on one-tape Turing machines

  • Authors:
  • Holger Petersen

  • Affiliations:
  • University of Stuttgart, Institute of Computer Science, Breitwiesenstr. 20-22, D-70565 Stuttgart, Germany

  • Venue:
  • Information Processing Letters
  • Year:
  • 2002

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Abstract

We disprove a conjecture of López-Ortiz by showing that the Element Distinctness Problem for n numbers of size O(logn) can be solved in O(n2(logn)3/2(loglogn)1/2) steps by a nondeterministic one-tape Turing machine. Further we give a simplified algorithm for solving the problem for shorter numbers in time O(n2 log n) on a deterministic one-tape Turing machine and a new proof of the matching lower bound.