On the divisibility of meet and join matrices

Let (P,⩽)=(P,∧,∨) be a lattice, let S={x1,x2,…,xn} be a meet-closed subset of P and let f:P→Z+ be a function. We characterize the matrix divisibility of the join matrix [S]f=[f(xi∨xj)] by the meet matrix (S)f=[f(xi∧xj)] in the ring Zn×n in terms of the usual divisibility in Z, and we present two algorithms for constructing certain classes of meet-closed sets S such that (S)f divides [S]f. As an example we present the lattice-theoretic structure of all meet-closed sets with at most five elements possessing the matrix divisibility property. Finally, we show that our methods solve some open problems in the divisor lattice, concerning the divisibility of GCD and LCM matrices.