数学物理学报(英文版) ›› 2022, Vol. 42 ›› Issue (2): 789-794.doi: 10.1007/s10473-022-0223-8
郝晶晶1, 董云柏2, 李磊3
Jingjing HAO1, Yunbai DONG2, Lei LI3
摘要: {For $1 < p < \infty$, let $S(L_p)_+$ be the set of positive elements in $L_p$ with norm one. Assume that $V_0: S(L_p(\Omega_1))_{+}\to S(L_p(\Omega_2))_{+}$ is a surjective norm-additive map; that is, \[\|V_0(x)+V_0(y)\|=\|x+y\|,\quad\forall\,x, y\in S(L_p(\Omega_1 ))_{+}.\] In this paper, we show that $V_0$ can be extended to an isometry from $L_p(\Omega_1)$ onto $L_p(\Omega_2)$.
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