On Sparse Parity Check Matrices

  • Authors:
  • Hanno Lefmann;Pavel Pudlák;Petr Savicky

  • Affiliations:
  • Universität Dortmund, FB Informatik, LS II, D-44221 Dortmund, Germany;Mathematical Institute, Academy of Sciences, Zitná 25, CZ–11567 Praha 1, Czech Republic;Institute of Computer Science, Academy of Sciences, Pod vodárenskou vezí 2, CZ-18200 Praha 8, Czech Republic

  • Venue:
  • Designs, Codes and Cryptography
  • Year:
  • 1997

Quantified Score

Hi-index 0.01

Visualization

Abstract

We consider the extremal problem to determine the maximalnumber N(m,k,r) of columns of a 0-1 matrix withm rows and at most r ones in each columnsuch that each k columns are linearly independentmodulo 2. For fixed integers k\geq 1and r≥ 1, we shall prove the probabilistic lowerbound N(m,k,r) = Ω (m^(kr/2(k-1))); for ka power of 2, we prove the upper bound N(m,k,r)=O(m^{\lceilkr/(k-1)\rceil /2}) which matches the lower bound forinfinitely many values of r. We give some explicitconstructions.