The geometry and topology of three-manifolds

The geometry and topology of three-manifolds is a rich and complex area of mathematics that deals with understanding the properties and structures of three-dimensional spaces (or manifolds). Here are the key concepts and themes involved: ### Manifolds A **manifold** is a topological space that locally resembles Euclidean space. An **n-manifold** is a space that is locally similar to \( \mathbb{R}^n \).