Studia Logica

, Volume 78, Issue 1–2, pp 349–356 | Cite as

Checking quasi-identities in a finite semigroup may be computationally hard

  • M. V. Volkov


We exhibit a 10-element semigroup Q such that the question “Does a given quasi-identity hold inQ?” is co-NP-complete while the question “Does a given identity hold inQ?” can be answered in linear time.


semigroup identity quasi-identity NP-completeness 


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Copyright information

© Kluwer Academic Publishers 2004

Authors and Affiliations

  • M. V. Volkov
    • 1
  1. 1.Department of Mathematics and MechanicsUral State UniversityEkaterinburgRussua

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