Rigid graphs in cylindrical normed spaces

Abstract

We characterise rigid graphs for cylindrical normed spaces $Z=X\oplus_\infty \mathbb{R}$ where $X$ is a finite dimensional real normed linear space and $Z$ is endowed with the product norm. In particular, we obtain purely combinatorial characterisations of minimal rigidity for a large class of 3-dimensional cylindrical normed spaces; for example, when $X$ is an $\ell_p$-plane with $p\in (1,\infty)$. We combine these results with recent work of Cros et al. to characterise rigid graphs in the 4-dimensional cylindrical space $(\mathbb{R}^2\oplus_1\mathbb{R})\oplus_\infty\mathbb{R}$. These are among the first combinatorial characterisations of rigid graphs in normed spaces of dimension greater than 2. Examples of rigid graphs are presented and algorithmic aspects are discussed.