The aim of this paper is to prove the following result: if X is a 2-dimensional symmetric real Banach space, then its self-length is greater than or equal to 2 pi. Moreover, the minimum value 2 pi is uniquely attained (up to isometries) by euclidean space.
机构:
Kangnam Univ, Fac Liberal Arts & Teaching, 40 Gangnam Ro, Yongin 16979, South KoreaKangnam Univ, Fac Liberal Arts & Teaching, 40 Gangnam Ro, Yongin 16979, South Korea