Robust Local Testability of Tensor Products of LDPC Codes

  • Irit Dinur
  • Madhu Sudan
  • Avi Wigderson
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4110)


Given two binary linear codes R and C, their tensor product RC consists of all matrices with rows in R and columns in C. We analyze the “robustness” of the following test for this code (suggested by Ben-Sasson and Sudan [6]): Pick a random row (or column) and check if the received word is in R (or C). Robustness of the test implies that if a matrix M is far from RC, then a significant fraction of the rows (or columns) of M are far from codewords of R (or C).

We show that this test is robust, provided one of the codes is what we refer to as smooth. We show that expander codes and locally-testable codes are smooth. This complements recent examples of P. Valiant [13] and Coppersmith and Rudra [9] of codes whose tensor product is not robustly testable.


Tensor Product Linear Code Parity Check Local View Testable Code 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Irit Dinur
    • 1
  • Madhu Sudan
    • 2
  • Avi Wigderson
    • 3
  1. 1.Hebrew UniversityJerusalemIsrael
  2. 2.Massachusetts Institute of TechnologyCambridge
  3. 3.Institute for Advanced StudyPrinceton

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