## Theory of Combinatorial Algorithms

Prof. Emo Welzl and Prof. Bernd Gärtner

# Mittagsseminar (in cooperation with M. Ghaffari, A. Steger and B. Sudakov)

 Mittagsseminar Talk Information

Date and Time: Wednesday, June 29, 2005, 12:15 pm

Duration: This information is not available in the database

Location: This information is not available in the database

Speaker: Vera Vértesi

## Identities in Algebras

Our major interest in this talk is the identity checking problem for finite algebras: for two given terms we want to decide whether they agree for every substitution over the algebra. This problem is always decidable, as one can check all the possible substitutions. So the usual question is to determine the complexity of the identity checking problem. It is easy to see that the problem is in coNP. For a certain kind of structures (like groups, rings, semigroups, etc.) usually we are interested in verifying that some kind of duality holds. That is, the identity checking problem is easy for some algebras and hard for the rest. In this talk I give a brief survey, how to prove that the identity checking problem is hard for a given finite algebra.

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