Ultraproduct

An ultraproduct is a construction in model theory, a branch of mathematical logic, that combines a family of structures into a new structure. The ultraproduct is useful in various areas such as algebra, topology, and set theory, particularly in the study of non-standard analysis and the preservation of properties between models. Here's a more formal description: 1. **Setting**: Let \((A_i)_{i \in I}\) be a collection of structures (e.g.