# 6. The Whitney Theorems

In this lecture we prove two celebrated theorems of Whitney:

- The
*Whitney Embedding Theorem*, which states any smooth manifold of dimension n may be embedded in $ \mathbb{R}^{2n}$ (we only prove a weaker version: namely that any compact smooth manifold of dimension $n$ may be embedded in $ \mathbb{R}^{2n+1}$). - The
*Whitney Approximation Theorem*, which states that a continuous map $ h \colon M \to N$ is homotopic to a smooth map $ \varphi \colon M \to N$. We will use this at the end of the semester to establish the*homotopy invariance property*of*de Rham cohomology***.**

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