Functions that have read-twice constant width branching programs are not necessarily testable

  • Authors:
  • Eldar Fischer;Ilan Newman;Jiří Sgall

  • Affiliations:
  • Department of Computer Science, The Technion, Haifa 32000, Israel;Department of Computer Science, University of Haifa, Haifa 31905, Israel;Mathematical Institute, AS CR, Zitná 25, CZ-11567 Praha 1, Czech Republic

  • Venue:
  • Random Structures & Algorithms
  • Year:
  • 2004

Quantified Score

Hi-index 0.00

Visualization

Abstract

We construct a property on 0/1-strings that has a representation by a collection of width-3 read-twice oblivious branching programs, but for which any two-sided ε-testing algorithm must query at least Ω(nδ) many queries for some fixed ε and δ. This shows that Newman's result [Testing of functions that have small width branching programs, SIAM J Comput 31 (2002), 1557-1570] cannot be generalized to read-k-times functions for k 1. In addition, we exhibit a property that has also a representation by a CNF formula of constant clause size. Hence, the nontestability results extend to properties that in addition have small (constant size) 0-witnesses.