Characterizations of Rotundity and Smoothness by Approximate Orthogonalities

[1] Alsina C., Sikorska J., Santos Tomás M., Norm Derivatives and Characterizations of Inner Product Spaces, World Scientific, Hackensack, New Jersay, 2009.10.1142/7452Search in Google Scholar

[2] Chmieliński J., Wójcik P., On a ρ-orthogonality, Aequationes Math. 80 (2010), 45–55.10.1007/s00010-010-0042-1Search in Google Scholar

[3] Chmieliński J., Wójcik P., ρ-orthogonality and its preservation – revisited, in: Recent Developments in Functional Equation and Inequalities, Banach Center Publ., Polish Acad. Sci. Inst. Math., Warsaw, 2013, pp. 17–30.10.4064/bc99-0-2Search in Google Scholar

[4] Dragomir S.S., Semi-inner products and applications, Nova Science Publishers, Inc., Hauppauge, New York, 2004.Search in Google Scholar

[5] Day M.M., Normed linear spaces, Ergeb. Math. Grenzgeb. 21, Springer, New York–Heidelberg, 1973.10.1007/978-3-662-09000-8Search in Google Scholar

[6] Giles J.R., Classes of semi-inner-product spaces, Trans. Amer. Math. Soc. 129 (1967), 436–446.10.1090/S0002-9947-1967-0217574-1Search in Google Scholar

[7] Lumer G., Semi-inner-product spaces, Trans. Amer. Math. Soc. 100 (1961), 29–43.10.1090/S0002-9947-1961-0133024-2Search in Google Scholar

[8] Wójcik P., Characterizations of smooth spaces by approximate orthogonalities, Aequationes Math. 89 (2015), 1189–1194.10.1007/s00010-014-0293-3Search in Google Scholar