Nichtaxiomatisierbarkeit von Satzmengen durch Ausdrücke spezieller Gestalt
Non standard arithmetic and application to height functions
Note on homomorphisms of direct products of algebras
On embedding models of arithmetic of cardinality ℵ₁ into reduced powers
In the early 1970’s S. Tennenbaum proved that all countable models of PA₁¯ + ∀₁ -Th(ℕ) are embeddable into the reduced product , where ℱ is the cofinite filter. In this paper we show that if M is a model of PA¯ + ∀₁ - Th(ℕ), and |M| = ℵ₁, then M is embeddable into , where D is any regular filter on ω.
On models of finite direct products of theories
On Reduced Products of Forcing Systems
On Representations in Banach Spaces.
On saturating ultrafilters on N
On the Boffa alternative
Let G* denote a nonprincipal ultrapower of a group G. In 1986 M.~Boffa posed a question equivalent to the following one: if G does not satisfy a positive law, does G* contain a free nonabelian subsemigroup? We give the affirmative answer to this question in the large class of groups containing all residually finite and all soluble groups, in fact, all groups considered in traditional textbooks on group theory.
On the simplicity and subdirect irreducibility of Boolean ultrapowers
Reduced powers of -trees
Remarks on limitultrapowers.
Representations of Orlicz lattices [Book]
Saturated Boolean Algebras With Ultrafilters
Saturated Boolean algebras with ultrafilters.
Separation properties and Boolean powers
Sheaf constructions in universal algebra and model theory
Some Remarks on Projective Model Classes and the Interpolation Theorem.
Some remarks on well-ordered models
Some Theorems For Model Theory Of Mixed-Valued Predicate Calculi