Congruence Representations of Join-homomorphisms of Finite Distributive Lattices: Size and Breadth
George Grätzer, H. Lakser, E. T. Schmidt · Journal of the Australian Mathematical Society Series A Pure Mathematics and Statistics · 2000
Abstract Let K and L be lattices, and let ϕ be a homomorphism of K into L.Then ϕ induces a natural 0-preserving join-homomorphism of Con K into Con L. Extending a result of Huhn, the authors proved that if D and E are finite distributive lattices and ψ is a 0-preserving join-homomorphism from D into E, then D and E can be represented as the congruence lattices of the finite lattices K and L, respectively, such that ψ is the natural 0-preserving join-homomorphism induced by a suitable homomorphism ϕ: K → L. Let m and n denote the number of join-irreducible elements of D and E, respectively, and let k = max (m, n). The lattice L constructed was of size O(22(n+m)) and of breadth n+m. We prove that K and L can be constructed as ‘small’ lattices of size O(k5) and of breadth three.