The elementary theory of Abelian groups with m-chains of pure subgroups
The elimination of descriptions from A. Bressan’s modal language on which the logical calculus is based
The equivalence of definable quantifiers in second order arithmetic
The role of the omitting types theorem in infinitary logic.
The theory of abelian p-groups with the quantifier I is decidable
The theory of Archimedean real closed fields in logics with Ramsey quantifiers
The theory of differentially closed fields in logics with cardinal quantifiers.
The unique existential quantifier.
Topological model theory with an interior operator: consistency properties and back - and forth arguments.