Let $n\in \mathbb{N}, n\geq 2.$ An element $x=(x_1, \ldots, x_n)\in E^n$ is called a {\em norming point} of $T\in {\mathcal L}(^n E)$ if $\|x_1\|=\cdots=\|x_n\|=1$ and$|T(x)|=\|T\|,$ where ${\mathcal denotes the space all continuous $n$-linear forms on $E.$For we define set} $T$
 \centerline{$\qopname\relax o{Norm}(T)=\Big\{(x_1, E^n: (x_1, x_n)~\mbox{is point of}~T\Big\}.$}
 By $i=(i...