Abstract : The join of two varieties is the smallest variety containing both. In finite semigroup theory, the varieties of R-trivial and L-trivial monoids are two of the most prominent classes of finite monoids. Their join is known to be decidable due to a result of Almeida and Azevedo. In this paper, we give a new proof for Almeida and Azevedo's effective characterization of the join of R-trivial and L-trivial monoids. This characterization is a single identity of omega-terms using three variables.
https://hal.inria.fr/hal-00992870
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Submitted on : Monday, May 19, 2014 - 1:57:30 PM Last modification on : Thursday, September 7, 2017 - 1:03:47 AM Long-term archiving on: : Monday, April 10, 2017 - 11:44:10 PM
Manfred Kufleitner, Alexander Lauser. The Join of the Varieties of R-trivial and L-trivial Monoids via Combinatorics on Words. Discrete Mathematics and Theoretical Computer Science, DMTCS, 2012, Vol. 14 no. 1 (1), pp.141-146. ⟨hal-00992870⟩