On the universal theory of the free pseudocomplemented distributive lattice

It is shown that the universal theory of the free pseudocomplemented distributive lattice is decidable and a recursive axiomatization is presented. This contrasts with the case of the full elementary theory of the finitely generated free algebras which is known to be undecidable. As a by-product, a description of the pseudocomplemented distributive lattices that can be embedded into the free algebra is also obtained.