Timeline for On compact operators with domain $c_{0}$
Current License: CC BY-SA 3.0
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Oct 3, 2015 at 21:34 | comment | added | Dongyang Chen | I forget the basic fact mainly because I have never taught functional analysis in my university. In fact, in my question, we can let $S=T^{*}J_{X}$, where $J_{X}:X\rightarrow X^{**}$ is the canonical embedding. Anyway, thanks, Bill. | |
Oct 3, 2015 at 18:47 | comment | added | Bill Johnson | Yes. If $T:Y\to X^*$ is even just weakly compact, then $T^{**}$ maps $Y^{**}$ into $X^*$ and extends $T$. In a first course in functional analysis one should learn that an bounded linear operator $S:V\to U$ is weakly compact if and only if $S^{**}V^{**} \subset U^{**}$. So this question is arguably more appropriate for another site. (I say ``arguably" because such a basic fact is probably hard to find in text books on real analysis.) | |
Oct 3, 2015 at 16:32 | history | asked | Dongyang Chen | CC BY-SA 3.0 |