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Erdős problem 671

For triangular arrays of nodes ain∈[−1,1]a_i^n\in[-1,1] let Lnf\mathcal{L}^nf be the Lagrange interpolation polynomials of a continuous ff, with fundamental polynomials pinp_i^n. Is there a choice of nodes such that for every continuous ff there is some xx where lim sup⁡n∑i∣pin(x)∣=∞\limsup_n \sum_i\lvert p_{i}^n(x)\rvert=\infty and yet Lnf(x)→f(x)\mathcal{L}^nf(x) \to f(x)? Is there a choice with lim sup⁡n∑i∣pin(x)∣=∞\limsup_n \sum_i\lvert p_{i}^n(x)\rvert=\infty for every xx, yet for every continuous ff some xx has Lnf(x)→f(x)\mathcal{L}^nf(x)\to f(x)? Both questions are claimed resolved in the affirmative.

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Problem row
sha256:a8df7a734f6f14295ef45f4f5ddb0303745f149e1017c6545557f08bbe4a36dd
Metadata
sha256:33ed7e9b2e5b9c955f06eec515c9840d75c5a8d299e45fc778bc4ed3e3a04f28
Observation
sha256:9c8326e865b6017b103af7611c852a06776d81964979b8ab5a1b800cd550dff6
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sha256:66971f19d9b6eb6ad02f672b5d33023ca13729774e0cdded9b2e73abecafdabe
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sha256:a956b84c437202e5a02cc9e036a621bd14a302b34a75758115730bdbb77c52a4
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sha256:a4a96441668a9f8b33afbcb3f696a2639f5fae145f36ddc063d7f67d5fb87ce8
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36c6d0fef71a3fec84d9dcd5eeca4e22e378f7cb