Halušková, Emília Algebras with one and two direct limits. (English) Zbl 0963.08002 Dorninger, D. (ed.) et al., Contributions to general algebra 12. Proceedings of the 58th workshop on general algebra “58. Arbeitstagung Allgemeine Algebra”, Vienna, Austria, June 3-6, 1999. Klagenfurt: Verlag Johannes Heyn. 211-219 (2000). Apart from the natural numbers with successor operation, a mono-unary algebra has no proper direct limit if and only if it has no proper retract. For mono-unary algebras each of whose components contains a cycle or the integers with successor operation, the existence of exactly one proper direct limit is equivalent to the existence of exactly one proper retract.For the entire collection see [Zbl 0942.00022]. Reviewer: Manfred Armbrust (Köln) Cited in 1 Document MSC: 08A60 Unary algebras 08B25 Products, amalgamated products, and other kinds of limits and colimits Keywords:mono-unary algebra; direct limit; retract PDFBibTeX XMLCite \textit{E. Halušková}, Contrib. Gen. Algebra 12, 211--219 (2000; Zbl 0963.08002)