Asymptotic and constructive methods for covering perfect hash families and covering arrays

Charles Colbourn, Erin Lanus, Kaushik Sarkar

Research output: Contribution to journalArticle

13 Scopus citations


Covering perfect hash families represent certain covering arrays compactly. Applying two probabilistic methods to covering perfect hash families improves upon the asymptotic upper bound for the minimum number of rows in a covering array with v symbols, k columns, and strength t. One bound can be realized by a randomized polynomial time construction algorithm using column resampling, while the other can be met by a deterministic polynomial time conditional expectation algorithm. Computational results are developed for both techniques. Further, a random extension algorithm further improves on the best known sizes for covering arrays in practice. An extensive set of computations with column resampling and random extension yields explicit constructions when (Formula presented.) for strength seven, (Formula presented.) for strength six, (Formula presented.) for strength five, and (Formula presented.) for strength four. When (Formula presented.), almost all known explicit constructions are improved upon. For strength (Formula presented.), restrictions on the covering perfect hash family ensure the presence of redundant rows in the covering array, which can be removed. Using restrictions and random extension, computations for (Formula presented.) and (Formula presented.) again improve upon known explicit constructions in the majority of cases. Computations for strengths three and four demonstrate that a conditional expectation algorithm can produce further improvements at the expense of a larger time and storage investment.

Original languageEnglish (US)
Pages (from-to)1-31
Number of pages31
JournalDesigns, Codes, and Cryptography
StateAccepted/In press - May 26 2017



  • Asymptotic bound
  • Conditional expectation algorithm
  • Covering array
  • Covering perfect hash family

ASJC Scopus subject areas

  • Computer Science Applications
  • Applied Mathematics

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