Abstract
In this paper we exhibit new classes of Banach spaces for which strong notions of optimization can be lifted from quotient spaces. Motivated by a well known result of Cheney and Wulbert on lifting of proximinality from a quotient space to a subspace, for closed subspaces, \(Z \subset Y \subset X\), we consider stronger forms of optimization, that Z has in X and the quotient space Y / Z has in X / Z should lead to the conclusion Y has the same property in X. The versions we consider have been studied under various names in the literature as L-proximinal subspaces or subspaces that have the strong-\(1\frac{1}{2}\)-ball property. We give an example where the strong-\(1\frac{1}{2}\)-ball property fails to lift to the quotient. We show that if every M-ideal in Y is a M-summand, for a finite codimensional subspace \(Z \subset Y\), that is a M-ideal in X with the strong-\(1\frac{1}{2}\)-ball property in X and if Y / Z has the \(1\frac{1}{2}\)-ball property in X / Z, then Y has the strong-\(1\frac{1}{2}\)-ball property in X.
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Bandyopadhyay, P., Lin, B.L., Rao, T.S.S.R.K.: Ball proximinality in Banach spaces, Banach spaces and their applications in analysis, pp. 251–264. Walter de Gruyter, Berlin (2007)
Cheney, E.W., Wulbert, D.E.: The existence and unicity of best approximations. Math. Scand. 24, 113–440 (1969)
Diestel, J., Uhl, J.J.: Vector Measures, Mathematical Surveys, No. 15, pp. xiii+322. American Mathematical Society, Providence (1977)
Harmand, P., Werner, D., Werner, W.: \(M\)-Ideals in Banach Spaces and Banach Algebras. Lecture Notes in Mathematics, vol. 1547. Springer, Berlin (1993)
Indumathi, V., Lalithambigai, S.: Ball proximinal spaces. J. Convex. Theory 18, 353–366 (2011)
Jayanarayanan, C.R., Paul, T.: Strong proximinality and intersection properties of balls in Banach spaces. J. Math. Anal. Appl. 426, 1217–1231 (2015)
Lin, P.-K., Zhang, W., Zheng, B.: Ball proximinal and strongly ball proximinal spaces. J. Convex. Anal. 22, 673–685 (2015)
Mena, J.F., Payá, R., Rodríguez, A., Yost, D.: Absolutely proximinal subspaces of Banach spaces. J. Approx. Theory 65, 46–72 (1991)
Payá, R., Yost, D.: The two-ball property: transitivity and examples. Mathematika 35, 190–197 (1988)
Yost, D.: Best approximation and intersections of balls in Banach spaces. Bull. Austral. Math. Soc. 20, 285–300 (1979)
Yost, D.: The \(n\)-ball properties in real and complex Banach spaces. Math. Scand. 50, 100–110 (1982)
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Rao, T.S.S.R.K. A Cheney and Wulbert type lifting theorem in optimization. Boll Unione Mat Ital 10, 585–589 (2017). https://doi.org/10.1007/s40574-016-0090-0
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DOI: https://doi.org/10.1007/s40574-016-0090-0