On the lattice of sub-pseudovarieties of DA

  title={On the lattice of sub-pseudovarieties of DA},
  author={Manfred Kufleitner and Pascal Weil},
  journal={Semigroup Forum},
The wealth of information that is available on the lattice of varieties of bands, is used to illuminate the structure of the lattice of sub-pseudovarieties of DA, a natural generalization of bands which plays an important role in language theory and in logic. The main result describes a hierarchy of decidable sub-pseudovarieties of DA in terms of iterated Mal’cev products with the pseudovarieties of definite and reverse definite semigroups. 
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