On the lattices of quasivarieties of differential groupoids
Aleksandr Kravchenko (2008)
Commentationes Mathematicae Universitatis Carolinae
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The main result of Romanowska A., Roszkowska B., , Demonstratio Math. (1987), no. 1–2, 277–290, provides us with an explicit description of the lattice of varieties of differential groupoids. In the present article, we show that this variety is -universal, which means that there is no convenient explicit description for the lattice of quasivarieties of differential groupoids. We also find an example of a subvariety of differential groupoids with a finite number of subquasivarieties. ...