The lattice of pseudovarieties of idempotent semigroups and a non-regular analogue
The lattice of pseudovarieties of idempotent semigroups and a non-regular analogue
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幂等半群和非正则类似物的伪簇格
DOI:
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发表时间:
1997
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通讯作者:
Pascal Weil
中科院分区:
文献类型:
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作者:
P. G. Trotter;Pascal Weil
Abstract. We use classical results on the lattice
$ cal L (cal B) $ of varieties of band (idempotent) semigroups to obtain information on the structure of the lattice Ps (DA) of subpseudovarieties of DA, – where DA is the largest pseudovariety of finite semigroups in which all regular semigroups are band semigroups. We bring forward a lattice congruence on Ps (DA), whose quotient is isomorphic to
$ cal L, (cal B) $, and whose classes are intervals with effectively computable least and greatest members. Also we characterize the pro-identities satisfied by the members of an important family of subpseudovarieties of DA. Finally, letting Vk be the pseudovariety generated by the k-generated elements of DA (k≥ 1), we use all our results to compute the position of the congruence class of Vk in
$ cal L (cal B ) $.