Poset algebras over well quasi-ordered posets

A new class of partial order-types, class G(bqo)(+), is defined and investigated here. A poset P is in the class G(bqo)(+) iff the poset algebra F (P) is generated by a better quasi-order G that is included in L(P). The free Boolean algebra F(P) and its free distributive lattice L(P) have been defined in [ABKR]. The free Boolean algebra F(P) contains the partial order P and is generated by it: F(P) has the following universal property. If B is any Boolean algebra and f is any order-preserving map from P into a Boolean algebra B, then f can be extended to a homomorphism (f) over cap of F(P) into B. We also define L(P) as the sublattice of F(P) generated by P. We prove that if P is any well quasi-ordering, then L(P) is well founded, and is a countable union of well quasi-orderings. We prove that the class G(bqo)(+) is contained in the class of well quasi-ordered sets. We prove that G(bqo)(+) is preserved under homomorphic image, finite products, and lexicographic sum over better quasi-ordered index sets. We prove also that every countable well quasi-ordered set is in G(bqo)(+). We do not know, however if the class of well quasi-ordered sets is contained in G(bqo)(+). Additional results concern homomorphic images of posets algebras.