Approximating the influence of monotone boolean functions in O(√n) query complexity

  • Authors:
  • Dana Ron;Ronitt Rubinfeld;Muli Safra;Omri Weinstein

  • Affiliations:
  • School of Electrical Engineering at Tel Aviv University, Israel;CSAIL at MIT, and the Blavatnik School of Computer Science at Tel Aviv University, Israel;Blavatnik School of Computer Science at Tel Aviv University;Computer Science Department, Princeton University

  • Venue:
  • APPROX'11/RANDOM'11 Proceedings of the 14th international workshop and 15th international conference on Approximation, randomization, and combinatorial optimization: algorithms and techniques
  • Year:
  • 2011

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Abstract

The Total Influence (Average Sensitivity) of a discrete function is one of its fundamental measures. We study the problem of approximating the total influence of a monotone Boolean function f : {0, 1}n → {0, 1}, which we denote by I[f]. We present a randomized algorithm that approximates the influence of such functions to within a multiplicative factor of (1 ± ε) by performing O(√n log n/I[f] poly(1/ε) queries. We also prove a lower bound of Ω(√n/log nċI[f]) on the query complexity of any constant-factor approximation algorithm for this problem (which holds for I[f] = Ω(1)), hence showing that our algorithm is almost optimal in terms of its dependence on n. For general functions we give a lower bound of Ω(n/I[f]), which matches the complexity of a simple sampling algorithm.