The strong divergence conjecture for arbitrary complete interpolating sequences

Let Λ={λn}nZ\Lambda = \{\lambda_n\}_{n\in\mathbb{Z}} be an arbitrary complete interpolating sequence with generator φ\varphi, and let {φn}nZ\{\varphi_n\}_{n\in\mathbb{Z}} be the corresponding interpolation kernels. For fPWπ1f\in\mathcal{PW}^{1}_{\pi}, define

(ANf)(t)=n=NNf(λn)φn(t).(\mathrm{A}_Nf)(t)=\sum_{n=-N}^{N}f(\lambda_n)\varphi_n(t).

Strong divergence conjecture. There exists an fPWπ1f\in\mathcal{PW}^{1}_{\pi} such that

limNANf=limNmaxtRn=NNf(λn)φn(t)=.\lim_{N\to\infty}\|\mathrm{A}_Nf\|_{\infty}=\lim_{N\to\infty}\max_{t\in\mathbb{R}}\left|\sum_{n=-N}^{N}f(\lambda_n)\varphi_n(t)\right|=\infty.

Strong divergence is known for sampling patterns arising from sine-type functions of the specified form; the conjecture extends this phenomenon to arbitrary complete interpolating sequences.

Sources & referencesView supporting material

Primary source

Holger Boche and Volker Pohl, “System Approximations and Generalized Measurements in Modern Sampling Theory”, arXiv:1410.5872 (2014).

Additional references

2 papers in this index state this conjecture (2014). The statement above is taken from the most recent of them; the others are arXiv:1404.4400.

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