English

Simplices with fixed volumes of codimension 2 faces in a continuous deformation

Metric Geometry 2025-01-22 v3 Combinatorics

Abstract

For any nn-dimensional simplex in the Euclidean space Rn\mathbb{R}^n with n4n\ge 4, it is asked that if a continuous deformation preserves the volumes of all the codimension 2 faces, then is it necessarily a \emph{rigid} motion. While the question remains open and the general belief is that the answer is affirmative, for all n4n\ge 4, we provide counterexamples to a variant of the question where Rn\mathbb{R}^n is replaced by a pseudo-Euclidean space Rp,np\mathbb{R}^{p,n-p} for some unspecified p2p\ge 2.

Keywords

Cite

@article{arxiv.2307.15817,
  title  = {Simplices with fixed volumes of codimension 2 faces in a continuous deformation},
  author = {Lizhao Zhang},
  journal= {arXiv preprint arXiv:2307.15817},
  year   = {2025}
}

Comments

18 pages, 3 figures. Added counterexample for $n=5$ in $\mathbb{R}^{p,5-p}$ (for some unspecified $p$) with fixed areas of all 2-faces