Paper detail

Differentiating along rectangles in lacunary directions

We show that, given some lacunary sequence of angles $\mathbfθ=(θ_j)_{j\in\N}$ not converging too fast to zero, it is possible to build a rare differentiation basis $\mathcal{B}$ of rectangles parallel to the axes that differentiates $L^1(\mathbb{R}^2)$ while the basis $\mathcal{B}_{\mathbfθ}$ obtained from $\mathcal{B}$ by allowing its elements to rotate around their lower left vertex by the angles $θ_j$, $j\in\mathbb{N}$, fails to differentiate all Orlicz spaces lying between $L^1(\mathbb{R}^2)$ and $L\log L(\mathbb{R}^2)$.