Well-definable types over subsets
What the finitization problem is not
When a first order T has limit models
We sort out to a large extent when a (first order complete theory) T has a superlimit model in a cardinal λ. Also we deal with related notions of being limit.
When is the orbit algebra of a group an integral domain ? Proof of a conjecture of P.J. Cameron
Cameron introduced the orbit algebra of a permutation group and conjectured that this algebra is an integral domain if and only if the group has no finite orbit. We prove that this conjecture holds and in fact that the age algebra of a relational structure R is an integral domain if and only if R is age-inexhaustible. We deduce these results from a combinatorial lemma asserting that if a product of two non-zero elements of a set algebra is zero then there is a finite common tranversal of their...
Whitehead Modules over Domains.
Wildness in the product groups
Non-abelian Polish groups arising as countable products of countable groups can be tame in arbitrarily complicated ways. This contrasts with some results of Solecki who revealed a very different picture in the abelian case.
Z specification of object oriented constraint programs.
Object oriented constraint programs (OOCPs) emerge as a leading evolution of constraint programming and artificial intelligence, first applied to a range of industrial applications called configuration problems. The rich variety of technical approaches to solving configuration problems (CLP(FD), CC(FD), DCSP, Terminological systems, constraint programs with set variables, . . . ) is a source of difficulty. No universally accepted formal language exists for communicating about OOCPs, which makes...
Zero-one laws for graphs with edge probabilities decaying with distance. Part II
Let Gₙ be the random graph on [n] = 1,...,n with the probability of i,j being an edge decaying as a power of the distance, specifically the probability being , where the constant α ∈ (0,1) is irrational. We analyze this theory using an appropriate weight function on a pair (A,B) of graphs and using an equivalence relation on B∖A. We then investigate the model theory of this theory, including a “finite compactness”. Lastly, as a consequence, we prove that the zero-one law (for first order logic)...
Zero-one laws for graphs with edge probabilities decaying with distance. Part I
Let Gₙ be the random graph on [n] = 1,...,n with the possible edge i,j having probability for j ≠ i, i+1, i-1 with α ∈ (0,1) irrational. We prove that the zero-one law (for first order logic) holds..
Zero-set property of o-minimal indefinitely Peano differentiable functions
Given an o-minimal expansion ℳ of a real closed field R which is not polynomially bounded. Let denote the definable indefinitely Peano differentiable functions. If we further assume that ℳ admits cell decomposition, each definable closed subset A of Rⁿ is the zero-set of a function f:Rⁿ → R. This implies approximation of definable continuous functions and gluing of functions defined on closed definable sets.
Zum L(Q)-Interpolationsproblem.
Zur Konstruktiven Deutung der semantischen Vollständigkeit klassischer Quantoren- und Modalkalküle.
-tautologies, uniform and non-uniform upper bounds in computation theory
Una -tautologia è una tautologia del tipo avente un solo interpolante di Craig , a meno di equivalenza logica. Utilizzando misure di complessità relative al problema di trovare tale , mostriamo come si possano ottenere limiti non uniformi di complessità mediante limiti uniformi, e viceversa.
Δ-extension and Hanf-numbers
-satisfiability, -consistency property, the downward Lowenheim Skolem theorem, and the failure of the interpolation theorem for with a strong limit cardinal of cofinality
- Théorie des ensembles
-porosity is separably determined
We prove a separable reduction theorem for -porosity of Suslin sets. In particular, if is a Suslin subset in a Banach space , then each separable subspace of can be enlarged to a separable subspace such that is -porous in if and only if is -porous in . Such a result is proved for several types of -porosity. The proof is done using the method of elementary submodels, hence the results can be combined with other separable reduction theorems. As an application we extend a theorem...
-categoricity of generalized products
-satisfiability, -consistency property, and the downward Lowenheim Skolem theorem for
ω-models of second order arithmetic and admissible sets