Complexity of hypersubstitutions and lattices of varieties
Thawhat Changphas ; Klaus Denecke
Discussiones Mathematicae - General Algebra and Applications, Tome 23 (2003), p. 31-43 / Harvested from The Polish Digital Mathematics Library

Hypersubstitutions are mappings which map operation symbols to terms. The set of all hypersubstitutions of a given type forms a monoid with respect to the composition of operations. Together with a second binary operation, to be written as addition, the set of all hypersubstitutions of a given type forms a left-seminearring. Monoids and left-seminearrings of hypersubstitutions can be used to describe complete sublattices of the lattice of all varieties of algebras of a given type. The complexity of a hypersubstitution can be measured by the complexity of the resulting terms. We prove that the set of all hypersubstitutions with a complexity greater than a given natural number forms a sub-left-seminearring of the left-seminearring of all hypersubstitutions of the considered type. Next we look to a special complexity measure, the operation symbol count op(t) of a term t and determine the greatest M-solid variety of semigroups where M=Hop is the left-seminearring of all hypersubstitutions for which the number of operation symbols occurring in the resulting term is greater than or equal to 2. For every n ≥ 1 and for M=Hop we determine the complete lattices of all M-solid varieties of semigroups.

Publié le : 2003-01-01
EUDML-ID : urn:eudml:doc:287626
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Thawhat Changphas; Klaus Denecke. Complexity of hypersubstitutions and lattices of varieties. Discussiones Mathematicae - General Algebra and Applications, Tome 23 (2003) pp. 31-43. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_7151_dmgaa_1062/

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