Testing Low-Degree Polynomials over Prime Fields

  • Authors:
  • Charanjit S. Jutla;Anindya C. Patthak;Atri Rudra;David Zuckerman

  • Affiliations:
  • IBM Thomas J. Watson Research Center;University of Texas at Austin;University of Washington;University of Texas at Austin

  • Venue:
  • FOCS '04 Proceedings of the 45th Annual IEEE Symposium on Foundations of Computer Science
  • Year:
  • 2004

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Abstract

We present an efficient randomized algorithm to test if a given function f : F_p^n\to F_p (where p is a prime) is a low-degree polynomial. This gives a local test for Generalized Reed-Muller codes over prime fields. For a given integer t and a given real 驴 0, the algorithm queries f at \frac{1}{\varepsilon } + t \cdot p^{\frac{{2t}}{{p - 1}} + 0(1)} points to determine whether f can be described by a polynomial of degree at most t. If f is indeed a polynomial of degree at most t, our algorithm always accepts, and if f has a relative distance at least \varepsilon from every degree t polynomial, then our algorithm rejects f with probability at least \frac{1}{2}. Our result is almost optimal since any such algorithm must query f on at least \Omega (\frac{1}{\varepsilon } + p^{\frac{{t + 1}}{{p - 1}}} ) points.