*Accepted Paper*

**Inserted:** 23 sep 2019

**Last Updated:** 14 jul 2021

**Journal:** J. Lond. Math. Soc.

**Year:** 2019

**Abstract:**

We prove criteria for $\mathcal{H}^k$-rectifiability of subsets of $\mathbb{R}^n$ with $C^{1,\alpha}$ maps, $0<\alpha\leq 1$, in terms of suitable approximate tangent paraboloids. We also provide a version for the case when there is not an a priori tangent plane, measuring on dyadic scales how close the set is to lying in a $k$-plane. We then discuss the relation with similar criteria involving Peter Jones' $\beta$ numbers, in particular proving that a sufficient condition is the boundedness for small $r$ of $r^{-\alpha}\beta_p(x,r)$ for $\mathcal{H}^k$-a.e. $x$ and for any $1\leq p\leq \infty$.

**Keywords:**
rectifiability, approximate tangent paraboloids, beta numbers, Holder maps

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