image of some ideal under the quotient map

47 Views Asked by At

enter image description here! I am still confused about the range of $\sigma(I_{\omega})$.Since $\|x_n\|_2\to 0,$we have $\|x_n\|\to 0$,$\sigma(I_{\omega})=0,$then $J=0$,it is trivial.

Is my understanding correct?enter image description here

1

There are 1 best solutions below

6
On BEST ANSWER

No, it is not true that if $\|x_n\|_2\to0$, then $\|x_n\|\to0$.

For instance, suppose that $k(n)=n$, $x_n=E_{11}$ for all $n$. Then $\|x_n\|_2=1/\sqrt n$, while $\|x_n\|=1$.