Critical points of pairs of varieties of algebras

dc.creatorGillibert, Pierre
dc.date2008-10-14
dc.date.accessioned2026-07-07T12:48:52Z
dc.date.available2026-07-07T12:48:52Z
dc.descriptionFor a class V of algebras, denote by Conc(V) the class of all semilattices isomorphic to the semilattice Conc(A) of all compact congruences of A, for some A in V. For classes V1 and V2 of algebras, we denote by crit(V1,V2) the smallest cardinality of a semilattice in Conc(V1) which is not in Conc(V2) if it exists, infinity otherwise. We prove a general theorem, with categorical flavor, that implies that for all finitely generated congruence-distributive varieties V1 and V2, crit(V1,V2) is either finite, or aleph_n for some natural number n, or infinity. We also find two finitely generated modular lattice varieties V1 and V2 such that crit(V1,V2)=aleph_1, thus answering a question by J. Tuma and F. Wehrung.
dc.identifierhttps://arxiv.org/abs/0810.2492
dc.identifierhttp://arxiv.org/abs/0810.2492
dc.identifierInternational Journal of Algebra and Computation 19, 1 (2009) Page 1-40
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/222207
dc.subjectRings and Algebras
dc.subject08A30 (Primary), 06B20, 08B25, 08B26 (Secondary)
dc.titleCritical points of pairs of varieties of algebras
dc.typetext

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