Sublattices of lattices of order-convex sets, III. The case of totally ordered sets

Marina V. Semenova (1) , Friedrich Wehrung (2)

1 Institute of Mathematics
2 LMNO - Laboratoire de Mathématiques Nicolas Oresme

For a partially ordered set P, let Co(P) denote the lattice of all order-convex subsets of P. For a positive integer n, we denote by SUB(LO) (resp., SUB(n)) the class of all lattices that can be embedded into a product of lattices of convex subsets of chains (resp., chains with at most n elements). We prove the following results: (1) Both classes SUB(LO) and SUB(n), for any positive integer n, are locally ?nite, ?nitely based varieties of lattices, and we ?nd ?nite equational bases of these varieties. (2) The variety SUB(LO) is the quasivariety join of all the varieties SUB(n), for 1 ? n < \omega, and it has only countably many subvarieties. We classify these varieties, together with all the ?nite subdirectly irreducible members of SUB(LO). (3) Every ?nite subdirectly irreducible member of SUB(LO) is projective within SUB(LO), and every subquasivariety of SUB(LO) is a variety.

Mots clés: join-seed; Lattice; embedding; poset; chain; order-convex; variety; join-irreducible; join-seed.

Domaines: Mathématiques générales [math.GM]

Marina V. Semenova, Friedrich Wehrung. Sublattices of lattices of order-convex sets, III. The case of totally ordered sets. International Journal of Algebra and Computation, 2004, 14 (3), pp.357-387. ⟨10.1142/S021819670400175X⟩. ⟨hal-00003977⟩