Balanced-refinement core conjecture for Lipschitz selections

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Let (M,ρ)({\mathcal M},\rho) be a pseudometric space, let XX be a Banach space, and let mm be a fixed positive integer. Set

ℓ=min⁡{m+1,dim⁡X},N(m,X)=2ℓ.\ell=\min\{m+1,\dim X\},\qquad N(m,X)=2^{\ell}.

For a set-valued mapping F:M→Km(X)F:{\mathcal M}\to{\mathcal K}_m(X), define its iterated balanced refinements by

F[0]=F,F[k+1](x)=⋂z∈M[F[k](z)+λk+1ρ(x,z)BX].F^{[0]}=F,\qquad F^{[k+1]}(x)=\bigcap_{z\in{\mathcal M}}\left[F^{[k]}(z)+\lambda_{k+1}\rho(x,z)B_X\right].

Here a set-valued mapping G:M→Km(X)G:{\mathcal M}\to{\mathcal K}_m(X) is a γ\gamma-core of FF when G(x)⊂F(x)G(x)\subset F(x) and dH⁡(G(x),G(y))≤γρ(x,y)\operatorname{d_H}(G(x),G(y))\le\gamma\rho(x,y) for all x,y∈Mx,y\in{\mathcal M}. Balanced-refinement core conjecture. There exist γ≥1\gamma\ge1 and numbers λ1,…,λℓ≥1\lambda_1,\ldots,\lambda_{\ell}\ge1 such that, whenever every restriction of FF to a subset of M{\mathcal M} of cardinality at most N(m,X)N(m,X) has a Lipschitz selection with seminorm at most 11, the mapping F[ℓ]F^{[\ell]} is a γ\gamma-core of FF. The conjecture proposes a finite iterative construction of a Lipschitz-controlled core from the local finiteness hypothesis underlying the Lipschitz selection principle.

References

Primary source

Pavel Shvartsman, “On the Core of a Low Dimensional Set-Valued Mapping”, arXiv:2102.07609 (2022).

Additional references

2 papers in this index state this conjecture (2020–2021). The statement above is taken from the most recent of them; the others are arXiv:2010.04540.

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