| Title: | On the lattices of quasivarieties of differential groupoids (English) | 
| Author: | Kravchenko, A. V. | 
| Language: | English | 
| Journal: | Commentationes Mathematicae Universitatis Carolinae | 
| ISSN: | 0010-2628 (print) | 
| ISSN: | 1213-7243 (online) | 
| Volume: | 49 | 
| Issue: | 1 | 
| Year: | 2008 | 
| Pages: | 11-17 | 
| . | 
| Category: | math | 
| . | 
| Summary: | The main result of Romanowska A., Roszkowska B., {\it On some groupoid modes\/}, Demonstratio Math. {\bf 20} (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 $\Cal Q$-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. (English) | 
| Keyword: | mode | 
| Keyword: | differential groupoid | 
| Keyword: | lattice of subquasivarieties | 
| Keyword: | $\Cal Q$-universal quasivariety | 
| MSC: | 08C15 | 
| MSC: | 20N02 | 
| idZBL: | Zbl 1212.08005 | 
| idMR: | MR2432816 | 
| . | 
| Date available: | 2009-05-05T17:06:06Z | 
| Last updated: | 2013-09-22 | 
| Stable URL: | http://hdl.handle.net/10338.dmlcz/119697 | 
| . | 
| Reference: | [1] Adams M.E., Adaricheva K.V., Dziobiak W., Kravchenko A.V.: Open problems related to the problem of Birkhoff and Maltsev.Studia Logica 78 (2004), 357-378. MR 2108035 | 
| Reference: | [2] Gorbunov V.A.: Algebraic Theory of Quasivarieties.Plenum New York-London-Moscow (1998). Zbl 0986.08001, MR 1654844 | 
| Reference: | [3] Ježek J., Kepka T.: Medial groupoids.Rozpravy Československé Akad. Věd, Řada Mat. Přírod. Věd 93 (1983), 2. MR 0734873 | 
| Reference: | [4] Płonka J.: On $k$-cyclic groupoids.Math. Japon. 30 (1985), 3 371-382. MR 0803288 | 
| Reference: | [5] Romanowska A.: On some representations of groupoid modes satisfying the reduction law.Demonstratio Math. 21 (1988), 4 943-960. Zbl 0677.20057, MR 0993839 | 
| Reference: | [6] Romanowska A., Roszkowska B.: On some groupoid modes.Demonstratio Math. 20 (1987), 1-2 277-290. Zbl 0669.08005, MR 0941422 | 
| Reference: | [7] Romanowska A., Roszkowska B.: Representation of $n$-cyclic groupoids.Algebra Universalis 26 (1989), 1 7-15. MR 0981422, 10.1007/BF01243869 | 
| Reference: | [8] Romanowska A.B., Smith J.D.H.: Differential groupoids.Contributions to General Algebra 7 Proc. Vienna Conf. (Vienna, 1990) 283-290 Teubner Stuttgart (1991). Zbl 0744.20055, MR 1143092 | 
| Reference: | [9] Romanowska A.B., Smith J.D.H.: Modes.World Scientific Singapore (2002). Zbl 1012.08001, MR 1932199 | 
| . |