@misc{NakamuraTanaka2026SphereRigidity,
  title         = {Rigidity of unit spheres in finite-dimensional real normed spaces},
  author        = {Nakamura, Jumpei and Tanaka, Ryotaro},
  year          = {2026},
  eprint        = {2609.31096},
  archivePrefix = {arXiv},
  primaryClass  = {math.FA},
  doi           = {10.48550/arXiv.2609.31096},
  url           = {https://arxiv.org/abs/2609.31096v1},
  note          = {Version 1}
}