HOMOMORPHISMS OF DISTRIBUTIVE LATTICES AS RESTRICTIONS OF CONGRUENCES .2. PLANARITY AND AUTOMORPHISMS

We prove that any {0,1}-preserving homomorphism of finite distributive lattices can be realized as the restriction of the congruence relations of a finite planar lattice with no nontrivial automorphisms to an ideal of that lattice, where this ideal also has no nontrivial automorphisms. We also prove that any {0, 1}-preserving homomorphism of finite distributive lattices with more than one element and any homomorphism of groups can be realized, simultaneously, as the restriction of the congruence relations and, respectively, the restriction of the automorphisms of a lattice L to those of an ideal of L; if the groups are both finite, then so is the lattice L.