In the paper, we present a necessary and sufficient condition for the existence of a sequence of measurable functions with finite values, which converge to any given essential bounded function in the topology of essential supremum in a Banach space. A new convergence method is proposed, which allows for the discovery of an essential bounded function $ F $ that is valued in a Banach space. Generally speaking, there exists a Banach-valued essential bounded function $ F $ which $ F_n $ can't converge to $ F $ in the topology of essential supremum for any sequence of finite-valued measurable function.
Citation: Yiheng Hu, Gang Lyu, Yuanfeng Jin, Qi Liu. Exploration of indispensable Banach-space valued functions[J]. AIMS Mathematics, 2023, 8(11): 27670-27683. doi: 10.3934/math.20231416
In the paper, we present a necessary and sufficient condition for the existence of a sequence of measurable functions with finite values, which converge to any given essential bounded function in the topology of essential supremum in a Banach space. A new convergence method is proposed, which allows for the discovery of an essential bounded function $ F $ that is valued in a Banach space. Generally speaking, there exists a Banach-valued essential bounded function $ F $ which $ F_n $ can't converge to $ F $ in the topology of essential supremum for any sequence of finite-valued measurable function.
[1] | W. Rudin, Real and complex analysis, In: The mathematical gazette, New York: McGraw-Hill, 52 (1974), 412. https://doi.org/doi:10.2307/3611894" target="_blank">10.2307/3611894">https://doi.org/doi:10.2307/3611894 |
[2] | J. A. Yan, Lecture notes on measure theory (Chinese), 2 Eds., Beijing: Science Press, 2004. |
[3] | M. Kreuter, Sobolev spaces of vector-valued functions, Ulam university, 2015. |
[4] | G. Q. Zhang, Y. Q. Lin, The lecture of functional analysis, Peking University Press, 1990. |
[5] | F. Zheng, C. Cui, A theorem on uniform convergence of operator series, J. Bohai Univ. (Nat. Sci. Ed.), 28 (2007), 338–339. https://doi.org/10.3969/j.issn.1673-0569.2007.04.010 doi: 10.3969/j.issn.1673-0569.2007.04.010 |
[6] | F. León-Saavedra, M. P. R. Rosa, S. Antonio, Orlicz-Pettis theorem through summability methods, Mathematics, 7 (2019), 895. https://doi.org/10.3390/math7100895 doi: 10.3390/math7100895 |
[7] | F. León-Saavedra, S. Moreno-Pulido, A. Sala, Orlicz-Pettis type theorems via strong $\rho$-Cesaro convergence, Numer. Funct. Anal. Optim., 40 (2019), 798–802. https://doi.org/10.1080/01630563.2018.1554587 doi: 10.1080/01630563.2018.1554587 |
[8] | F. León-Saavedra, F. J. Pérez-Fernández, F. P. R. Rosa, A. Sala, Ideal convergence and completeness of a normed space, Mathematics, 7 (2019), 897. https://doi.org/10.3390/math7100897 doi: 10.3390/math7100897 |
[9] | F. León-Saavedra, S. Moreno-Pulido, A. Sala-Pérez, Completeness of a normed space via strong $\rho$-Cesàro summability, Filomat, 33 (2019), 3013–3022. https://doi.org/10.2298/FIL1910013L doi: 10.2298/FIL1910013L |
[10] | J. Diestel, J. J. Uhl, Jr., Vector measures, American mathematical society, 15 (1977). http://doi.org/10.1090/surv/015 doi: 10.1090/surv/015 |
[11] | D. X. Xia, S. Z. Yan, W. C. Shu, Y. S. Tong, Functional analysis (Second tutorial) (Chinese), Higher education press, 2008. |