Testing juntas

Eldar Fischer*, Guy Kindler, Dana Ron, Shmuel Safra, Alex Samorodnitsky

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

84 Scopus citations


We show that a boolean valued function over n variables, where each variable ranges in an arbitrary probability space, can be tested for the property of depending on only J of them using a number of queries that depends only polynomially on J and the approximation parameter ε. We present several tests that require a number of queries that is polynomial in J and linear in ε-1. We show a non-adaptive test that has one-sided error, an adaptive version of it that requires fewer queries, and a non-adaptive two-sided version of the test that requires the least number of queries. We also show a two-sided non-adaptive test that applies to functions over n boolean variables, and has a more compact analysis. We then provide a lower bound of Ω̃(J) on the number of queries required for the non-adaptive testing of the above property; a lower bound of Ω(log(J+1)) for adaptive algorithms naturally follows from this. In establishing this lower bound we also prove a result about random walks on the group Zq2 that may be interesting in its own right. We show that for some t(q)=Õ(q 2), the distributions of the random walk at times t and t+2 are close to each other, independently of the step distribution of the walk. We also discuss related questions. In Particular, when given in advance a known J-junta function h, we show how to test a function for the property of being identical to h up to a permutation of the variables, in a number of queries that is polynomial in J and ε-1.

Original languageAmerican English
Pages (from-to)753-787
Number of pages35
JournalJournal of Computer and System Sciences
Issue number4
StatePublished - Jun 2004

Bibliographical note

Funding Information:
·Corresponding author. E-mail address: eldar@cs.technion.ac.il (E. Fischer). 1Research supported by a Technion VPR fund Dent Charitable Trust, non-military research fund, and by a joint Haifa University–Technion research fund. 2Research supported by the Israel Science Foundation (Grant 32/00-1). 3Research supported by an Israeli Science Foundation grant and a United States–Israel Binational Science Foundation grant. 4Research supported by the Israel Science Foundation (Grant 039-7165).


  • Boolean functions
  • Discrete Fourier Analysis
  • Juntas
  • Property testing


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