Complete congruence lattices of two related modular lattices

Abstract

By a 1991 result of R. Freese, G. Gratzer, and E. T. Schmidt, every complete lattice A is isomorphic to the lattice Com(K) of complete congruences of a strongly atomic, 3-distributive, complete modular lattice K. In 2002, Gratzer and Schmidt improved 3-distributivity to 2-distributivity. Here, we represent morphisms between two complete lattices with complete lattice congruences in three ways. Namely, for \({i \in \{1, 2, 3\},}\) let \({A_i}\) and \({A^{\prime}_{i}}\) be arbitrary complete lattices and let \({f_i}\) : \({A_{i} \rightarrow A^{\prime}_{i}}\) be maps such that (i) \({f_1}\) is \({(\bigvee, 0)}\)-preserving and 0-separating, (ii) \({f_2}\) is \({(\bigwedge, 0, 1)}\)-preserving, and (iii) \({f_3}\) is \({(\bigvee, 0)}\)-preserving. We prove that for \({i \in \{1, 2, 3\},}\) there exist strongly atomic, 2-distributive, complete modular lattices \({K_i}\) and \({K^{\prime}_{i}}\) such that \({A_{i} \cong {\rm Com}({K_{i}}), A^{\prime}_{i} \cong {\rm Com}({K^{\prime}_{i}}),}\) and, in addition, (i) \({K_1}\) is a principal ideal of \({{K^{\prime}_{1}}}\) and \({f_1}\) is represented by complete congruence extension, (ii) \({K^{\prime}_{2}}\) is a sublattice of \({K_2}\) and \({f_2}\) is represented by restriction, and (iii) \({f_3}\) is represented as the composite of a map naturally induced by a complete lattice homomorphism from \({K_3}\) to \({K^{\prime}_{3}}\) and the complete congruence generation in \({K^{\prime}_{3}}\). Also, our approach yields a relatively easy construction that proves the above-mentioned 2002 result of Gratzer and Schmidt.