A **4-manifold** is a type of mathematical object studied in the field of topology and differential geometry. In general, an **n-manifold** is a space that locally resembles Euclidean space of dimension \( n \). This means that around every point in a 4-manifold, there exists a neighborhood that is homeomorphic (structurally similar) to an open subset of \( \mathbb{R}^4 \).
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