Laterally complete and projective hulls of semilinear residuated lattices

Abstract

The existence of lateral completions of ℓ-groups is an old problem that was first solved, for conditionally complete vector lattices, by Nakano. The existence and uniqueness of lateral completions of representable ℓ-groups was first obtained as a consequence of the orthocompletions of Bernau, and later the proofs were simplified by Conrad, who also proved the existence and uniqueness of lateral completions of ℓ-groups with zero radical. Finally, Bernau solved the problem for ℓ-groups in general.In this work, we address the problem of the existence and uniqueness of lateral, projectable, and strongly projectable completions of residuated lattices. In particular, we push the methods of Conrad through to the case of the representable GMV-algebras.The leading idea is to construct, for any given semilinear residuated lattice, an orthocomplete extension such that the former is dense in the latter. This extension is obtained as the direct limit of a family of residuated lattices that are constructed using maximal partitions of the algebra of polars of the original residuated lattice.In order to complete the proof we still need another hypothesis, which is an abstraction of the condition of double negation in which commutativity and integrality have been dropped, and determines the wide class of Generalized MV-algebras. This, together with the density, allows us to obtain the completions of the given residuated lattice.