Dec 10, 2010 · We also obtain decidability of the problem when we replace primitive positive definability by existential positive, or existential definability.

Motivation and the main result. When studying a countably infinite relational structure 0, we often wish to know what © can express by its relations; ...

We also obtain decidability of the problem when we replace primitive positive definability by existential positive, or existential definability. Our proof makes ...

For instance, our result shows that it is decidable whether a given relation from Allen's Interval. Algebra [2, 22] is primitive positive definable in a given ...

Feb 11, 2021 · Abstract page for arXiv paper 2102.06160: Decidability of definability issues in the theory of real addition.

This provides a topological characterization of first-order definability in the structure 〈ℝ, +, <, 1〉. It also allows us to deliver a self-definable ...

We also obtain decidability of the problem when we replace primitive positive definability by existential positive, or existential definability. Our proof makes ...

Decidability of the problem is shown for all structures Gamma that have a first-order definition in an ordered homogeneous structure Delta with a finite ...

... Decidability ... We also obtain decidability of the problem when we replace primitive positive definability by existential positive, or existential definability.

Thus, restricted to countably infinite structures, predicate and formula circumscription define the same sets and have equally difficult decision problems. With ...