New Upper Bounds on the Average PTF Density of Boolean Functions

  • Kazuyuki Amano
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 6506)


A Boolean function f:{1, − 1} n →{1, − 1} is said to be sign-represented by a real polynomial \(p:{\mathbb R}^n \rightarrow {\mathbb R}\) if sgn(p(x)) = f(x) for all x ∈ {1, − 1} n . The PTF density of f is the minimum number of monomials in a polynomial that sign-represents f. It is well known that every n-variable Boolean function has PTF density at most 2 n . However, in general, less monomials are enough. In this paper, we present a method that reduces the problem of upper bounding the average PTF density of n-variable Boolean functions to the computation of (some modified version of) average PTF density of k-variable Boolean functions for small k. By using this method, we show that almost all n-variable Boolean functions have PTF density at most (0.617) 2 n , which is the best upper bound so far.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2010

Authors and Affiliations

  • Kazuyuki Amano
    • 1
  1. 1.Dept of Comp SciGunma UnivGunmaJapan

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