
Journal of Convex Analysis 28 (2021), No. 1, 041054 Copyright Heldermann Verlag 2021 Daugavet and DeltaPoints in Absolute Sums of Banach Spaces Rainis Haller Institute of Mathematics and Statistics, University of Tartu, 51009 Tartu, Estonia rainis.haller@ut.ee Katriin Pirk Institute of Mathematics and Statistics, University of Tartu, 51009 Tartu, Estonia katriin.pirk@ut.ee Triinu Veeorg Institute of Mathematics and Statistics, University of Tartu, 51009 Tartu, Estonia triinu.veeorg@gmail.com A Daugavetpoint (resp. Δpoint) of a Banach space is a norm one element x for which every point in the unit ball (resp. element x itself) is in the closed convex hull of unit ball elements that are almost at distance 2 from x. A Banach space has the wellknown Daugavet property (resp. diametral local diameter 2 property) if and only if every norm one element is a Daugavetpoint (resp. Δpoint). Our results complement the ones of T.A.Abrahamsen, R.Haller, V.Lima and K.Pirk [Delta and Daugavetpoints in Banach spaces, Proc. Edinb. Math. Soc. 63/2 (2020) 475496] concerning the existence of Daugavet and Δpoints in absolute sums of Banach spaces. Keywords: Daugavet property, Daugavet point, deltapoint, absolute sum, diameter two property. MSC: 46B20, 46B04. [ Fulltextpdf (117 KB)] for subscribers only. 