The complex cross-2 Banach–Mazur distance conjecture

From papers

For n1n\geq 1, let pn(C)\ell_p^n(\mathbb{C}) denote the nn-dimensional complex sequence space with exponent pp, and let dBMd_{BM} denote the Banach–Mazur distance. For 1q2p1\leq q\leq 2\leq p\leq\infty, define

α=max{121p,1q12}.\alpha=\max\left\{\frac{1}{2}-\frac{1}{p},\frac{1}{q}-\frac{1}{2}\right\}.

The complex cross-2 distance conjecture. For every integer n1n\geq 1 and all 1q2p1\leq q\leq 2\leq p\leq\infty,

dBM(pn(C),qn(C))=nα.d_{BM}\bigl(\ell_p^n(\mathbb{C}),\ell_q^n(\mathbb{C})\bigr)=n^{\alpha}.

This extends the proposed exact formula for the complex distance between 1n\ell_1^n and n\ell_{\infty}^n to exponents on opposite sides of 22. The source gives the corresponding order estimates and says that exact values in this regime are generally unknown; no resolution is supplied.

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Sources & referencesView supporting material

Primary source

Tomasz Kobos and Marin Varivoda, “A Complex Analogue of Spencer's Six Standard Deviations Theorem and the Complex Banach-Mazur Distance”, arXiv:2602.12868 (2026).

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