 Hierarchy (mathematics)

In mathematics, a "hierarchy" often refers to a structured arrangement of concepts, objects, or systems that are organized according to specific relationships or levels of complexity. Different areas of mathematics may have their own hierarchies. Here are a few contexts in which the term is commonly used: 1. **Set Theory**: In set theory, the hierarchy can refer to the classification of sets based on their cardinality, including finite sets, countably infinite sets, and uncountably infinite sets.