Heine–Borel theorem

The Heine–Borel theorem is a fundamental result in real analysis and topology that characterizes compact subsets of Euclidean space. The theorem states that in \(\mathbb{R}^n\), a subset is compact if and only if it is closed and bounded. To elaborate: 1. **Compact Set**: A set \( K \) is compact if every open cover of \( K \) has a finite subcover.