Higher amalgamation in $\mathrm{ACFA}^{+}$
Abstract
We show two results on higher amalgamation in the theory $\mathrm{ACFA}^{+}$, the model companion of the theory of difference fields with an additive character (added as a continuous logic predicate) on the fixed field in characteristic 0. On one hand, we show that the non-trivial condition for 3-amalgamation established in a preceding paper is not sufficient for 4-amalgamation. On the other hand, we show that when working over substructures whose $\mathcal{L}_σ$-reduct is a model of $\mathrm{ACFA}$, $n$-amalgamation holds for all $n\geq 3$.
Fields of Study & Subjects
Advanced Topology and Set Theory
Rings
Modules
and Algebras
Advanced Algebra and Logic
Publication details
- Journal / source
- arXiv (Cornell University)
- Publication date
- 8 January 2026
- Document type
- Preprint