In this paper, we study the problem of isometric extension on the unit sphere of the space $l\cap l^p(H)$ for $0 < p < 1$. We obtain that an isometric mapping of the unit sphere $S(l\cap l^p(H))$ onto itself can be extended to an isometry on the whole space $l\cap l^p(H)$.
Ann. Funct. Anal.
6(3):
87-95
(2015).
DOI: 10.15352/afa/06-3-8
