Sequeira, Margarida Varieties of Ockham algebras satisfying \(x\leq f^ 4(x)\). (English) Zbl 0678.06006 Port. Math. 45, No. 4, 369-391 (1988). An Ockham algebra is a bounded distributive lattice on which there is defined a dual endomorphism f. The subvariety of MS-algebras is obtained by imposing the restriction \(id\leq f^ 2\). Here, the author considers the subvariety obtained by imposing the restriction \(id\leq f^ 4\). A complete characterization is given of all the subvarieties, both by identities and by special subsets. Verification of the results by computer is mentioned. Reviewer: T.S.Blyth Cited in 2 Documents MSC: 06D30 De Morgan algebras, Łukasiewicz algebras (lattice-theoretic aspects) 08B99 Varieties Keywords:Ockham algebra; subvariety; identities PDFBibTeX XMLCite \textit{M. Sequeira}, Port. Math. 45, No. 4, 369--391 (1988; Zbl 0678.06006) Full Text: EuDML