Naor's finite analogue of the Cornulier–Tessera–Valette conjecture

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Let {Gn}n\{G_n\}_n be a sequence of finite groups with sup⁡nrank⁡(Gn)<∞\sup_n \operatorname{rank}(G_n)<\infty. For a generating set SS of size rr, let dSd_S be the associated word metric, and let c2(Gn,dS)c_2(G_n,d_S) denote its infimal bi-Lipschitz distortion into Hilbert space. For S∈(Gnr)S\in {G_n\choose r}, write ⟨S⟩=Gn\langle S\rangle=G_n. Naor's finite conjecture. The following five conditions are equivalent:

  1. For all r>sup⁡nrank⁡(Gn)r>\sup_n \operatorname{rank}(G_n),
sup⁡nsup⁡S∈(Gnr):⟨S⟩=Gnc2(Gn,dS)<∞.\sup_n\sup_{S\in {G_n\choose r}:\langle S\rangle=G_n}c_2(G_n,d_S)<\infty.
  1. There exists r∈Nr\in\mathbb{N} such that
sup⁡nsup⁡S∈(Gnr):⟨S⟩=Gnc2(Gn,dS)<∞.\sup_n\sup_{S\in {G_n\choose r}:\langle S\rangle=G_n}c_2(G_n,d_S)<\infty.
  1. For all r>sup⁡nrank⁡(Gn)r>\sup_n \operatorname{rank}(G_n), there are generating sets SnS_n of size rr such that
sup⁡ninf⁡S∈(Gnr):⟨S⟩=Gnc2(Gn,dS)<∞.\sup_n\inf_{S\in {G_n\choose r}:\langle S\rangle=G_n}c_2(G_n,d_S)<\infty.
  1. There exists r∈Nr\in\mathbb{N} and generating sets SnS_n of size rr such that
sup⁡ninf⁡S∈(Gnr):⟨S⟩=Gnc2(Gn,dS)<∞.\sup_n\inf_{S\in {G_n\choose r}:\langle S\rangle=G_n}c_2(G_n,d_S)<\infty.
  1. There exists r∈Nr\in\mathbb{N} and, for each GnG_n, an abelian subgroup Hn≤GnH_n\leq G_n of rank at most rr such that
sup⁡n[Gn:Hn]<∞.\sup_n[G_n:H_n]<\infty.

The conjecture is a finite-group analogue of the assertion that Hilbert-space embeddability forces virtual abelianness. Its status is not resolved in the supplied source context.

References

Primary source

Cosmas Kravaris, “L_1 and L_2 embeddings of the symmetric group”, arXiv:2512.09226 (2026).

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