Some characterizations of inner product spaces based on angle

Authors : S.m.s. NABAVİ SALES

Pages : 626-632

Doi:10.15672/hujms.574044

View : 14 | Download : 4

Publication Date : 2019-06-15

Article Type : Research Paper

Abstract :A problem in functional analysis that  arises naturally is about finding necessary and sufficient conditions for a normed space to be an inner product space. By answering this question, mathematicians try to understand the inner product and normed spaces features. In this note, we have discussed this issue and we prove some results concerned with it. We introduce a notion of angle between two vectors in a normed space, denoted by $A_\thetainsert ignore into journalissuearticles values(.,.);$ where $\theta\neq{k\pi\over2}$. We also speak about a notion of orthogonality concerning it, we call it $\theta$-orthogonality.
Keywords : inner product, normed space, angle, orthogonality