Coping with errors in binary search procedures

R. L. Rivest, A. R. Meyer, D. J. Kleitman, K. Winklmann, J. Spencer

Research output: Contribution to journalConference articlepeer-review


We consider the problem of identifying an unknown value xe{l, 2,⋯,n} using only comparisons of x to constants when as many as E of 'the comparisons may receive erroneous answers. For a continuous analogue of this problem we show that there is a unique strategy that is optimal in the worst case. This strategy for the continuous problem is then shown to yield a strategy for the original discrete problem that uses log2n+E-log2log2n+O(E-Iog2E) comparisons in the worst case. This number is shown to be optimal even if arbitrary "Yes-No" questions are allowed. We show that a modified version of this search problem with errors is equivalent to the problem of finding the minimal root of a set of increasing functions. The modified version is then also shown to be of complexity log2n+E-log2log2n+0(E-log2E).

Original languageEnglish (US)
Pages (from-to)227-232
Number of pages6
JournalProceedings of the Annual ACM Symposium on Theory of Computing
StatePublished - May 1 1978
Event10th Annual ACM Symposium on Theory of Computing, STOC 1978 - San Diego, United States
Duration: May 1 1978May 3 1978

ASJC Scopus subject areas

  • Software


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