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Upper-modular elements of the lattice of semigroup varieties - MaRDI portal

Upper-modular elements of the lattice of semigroup varieties (Q1001463)

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scientific article; zbMATH DE number 5508756
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Upper-modular elements of the lattice of semigroup varieties
scientific article; zbMATH DE number 5508756

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    Upper-modular elements of the lattice of semigroup varieties (English)
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    17 February 2009
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    The author proves that if a proper semigroup variety \(\mathbf V\) is an upper-modular element in the lattice of all semigroup varieties, then \(\mathbf V\) is periodic and the largest nil-subvariety of \(\mathbf V\) satisfies the identities \(xy=yx\), \(x^2y=xy^2\). This allows the author to classify all commutative varieties that are upper-modular elements in the lattice of all semigroup varieties.
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    semigroup variety
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    lattice of semigroup varieties
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    upper-modular element
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    periodic variety
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    nilvariety
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    variety of finite index
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