| Title:
|
On the proof of Erdős' inequality (English) |
| Author:
|
Zhu, Lai-Yi |
| Author:
|
Zhou, Da-Peng |
| Language:
|
English |
| Journal:
|
Czechoslovak Mathematical Journal |
| ISSN:
|
0011-4642 (print) |
| ISSN:
|
1572-9141 (online) |
| Volume:
|
67 |
| Issue:
|
4 |
| Year:
|
2017 |
| Pages:
|
967-979 |
| Summary lang:
|
English |
| . |
| Category:
|
math |
| . |
| Summary:
|
Using undergraduate calculus, we give a direct elementary proof of a sharp Markov-type inequality $\|p'\|_{[-1,1]}\leq \frac 12\|p\|_{[-1,1]}$ for a constrained polynomial $p$ of degree at most $n$, initially claimed by P. Erd\H os, which is different from the one in the paper of T. Erdélyi (2015). Whereafter, we give the situations on which the equality holds. On the basis of this inequality, we study the monotone polynomial which has only real zeros all but one outside of the interval $(-1,1)$ and establish a new asymptotically sharp inequality. (English) |
| Keyword:
|
polynomial |
| Keyword:
|
Erd\H os' inequality |
| Keyword:
|
undergraduate calculus |
| Keyword:
|
monotone polynomial |
| MSC:
|
26D05 |
| MSC:
|
41A17 |
| MSC:
|
42A05 |
| idZBL:
|
Zbl 06819566 |
| idMR:
|
MR3736012 |
| DOI:
|
10.21136/CMJ.2017.0256-16 |
| . |
| Date available:
|
2017-11-20T14:53:56Z |
| Last updated:
|
2020-07-03 |
| Stable URL:
|
http://hdl.handle.net/10338.dmlcz/146960 |
| . |
| Reference:
|
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| Reference:
|
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| Reference:
|
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| Reference:
|
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| Reference:
|
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| Reference:
|
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| Reference:
|
[7] Lax, P. D.: Proof of a conjecture of P. Erdős on the derivative of a polynomial.Bull. Am. Math. Soc. 50 (1944), 509-513. Zbl 0061.01802, MR 0010731, 10.1090/S0002-9904-1944-08177-9 |
| Reference:
|
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| . |
