New type parallelogram laws in Banach spaces and geodesic spaces with curvature bounded above
Yasunori Kimura, Shuta Sudo · Arabian Journal of Mathematics · 2022
Abstract The parallelogram law characterizes a part of the structure of Hilbert spaces. To hold the parallelogram law by the norm, reasonably good conditions are required for Banach spaces. This paper proposes new type parallelogram laws with bifunctions on Banach spaces and geodesic spaces, respectively.