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7:08 AM

@Glorfindel Would the information that sometimes replacing xahlee.org with xahlee.info leads to a working link be useful for your script?

dead-links Search returns 127 posts with xahlee.org networkwide.

Here is an example where the replacement returned a working page - from Wikipedia.

And here is an instance where simply changing xahlee.org/UnixResource_dir/unix_shell_text_processing.html to xahlee.info/UnixResource_dir/unix_shell_text_processing.html doesn't work.

A: Good tutorial on grep, sort, unique and tools like that

What you are looking may fit in "Text processing". This is a quick introduction: http://xahlee.org/UnixResource_dir/unix_shell_text_processing.html

The link seems to be dead - here is a Wayback Machine snapshot. Looking into the new domain xahlee.info, I did not find something exactly like this - but this is similar: Linux: Text Processing: grep, cat, awk, uniq. — Martin 5 mins ago

Glorfindel

7:23 AM

@MartinSleziak that's certainly useful; my script checks whether the new URL is working or not; otherwise it'll try to find a Wayback Machine copy.

I'll put it on my to-do list, thanks!

Martin Sleziak

Thanks for the response (and for looking into this)!

Hmm... now I see that in another instance replacing http://xahlee.org/emacs with http://xahlee.info/emacs/emacs worked: tex.stackexchange.com/posts/29222/revisions

@Glorfindel So maybe the conversion might be more complex - at least in some cases....?

Again, if I try search there are 72 posts with xahlee.org/emacs.

Glorfindel

seems so, yes

it sometimes helps to search for the literal content of a Wayback Machine snapshot

that way you can discover a lot of substitution rules

but any observations are most welcome!

1 hour later…

Martin Sleziak

8:45 AM

Q: Example of Whitney Extension

Let $f:X\rightarrow \mathbb{R}$ be a function where $X\subseteq \mathbb{R}^n$ is a non-empty set. In this wonderful paper, Fefferman essentially show that if $f$ admits a degree $k-1$ polynomial extension on all finite subsets of a given size, then it admits a $C^{k,1}$-extension to all of $\mat...