Efficiently Testing Sparse GF(2) Polynomials

  • Authors:
  • Ilias Diakonikolas;Homin K. Lee;Kevin Matulef;Rocco A. Servedio;Andrew Wan

  • Affiliations:
  • No Affiliations, ;No Affiliations, ;No Affiliations, ;No Affiliations, ;No Affiliations,

  • Venue:
  • ICALP '08 Proceedings of the 35th international colloquium on Automata, Languages and Programming, Part I
  • Year:
  • 2008

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Abstract

We give the first algorithm that is both query-efficient andtime-efficient for testing whether an unknown function f:{0,1}n →{0,1} is an s-sparseGF(2) polynomial versus ε-far from everysuch polynomial. Our algorithm makespoly(s,1/ε) black-box queries tof and runs in time n·poly(s,1/ε). The only previousalgorithm for this testing problem [DLM + 07] usedpoly(s,1/ε) queries, but had running timeexponential in s and super-polynomial in1/ε.Our approach significantly extends the "testing by implicitlearning" methodology of [DLM + 07]. The learningcomponent of that earlier work was a brute-force exhaustive searchover a concept class to find a hypothesis consistent with a sampleof random examples. In this work, the learning component is asophisticated exact learning algorithm for sparse GF(2)polynomials due to Schapire and Sellie [SS96]. A crucial element ofthis work, which enables us to simulate the membership queriesrequired by [SS96], is an analysis establishing new properties ofhow sparse GF(2) polynomials simplify under certainrestrictions of "low-influence" sets of variables.