I recently fixed a broken link to a PlanetMath page, by changing
Some links also have
.html at the end, without
/encyclopedia/ see e.g.
http://planetmath.org/FullyIndecomposableMatrix.html from this Answer.
I also found some other links that I cannot understand, but now link to the homepage. These links start with
planetmath.org/?op and now redirect to the homepage. I'm not sure what they were supposed to link to, however. I found this by performing a search for PlanetMath on MO. An example post there is this one.
As mentioned by Glorfindel, some posts are not fixed by the above procedure. I would guess that some pages have been renamed or deleted. It might be worth pointing out that PlanetMath has an index page which we can use to check before making the change.
Here are the posts that we can be sure have broken links:
Searching$^2$ with url:"*planetmath.org/?op*" gives a further 17 hits.
Trying to find posts with
.htmlat the end: url:"*planetmath.org/*html" gives 248 results. If the wildcard
*works in the middle of the search input, this should strictly contain the results of point 1.
Are there other possible formats of PlanetMath links that are now broken?
How shall we go about fixing the links?
1. Note: searching for
"PlanetMath" only gives 146 hits, but "url:"*planetmath.org/*"" gives 953 hits. So searching just for the website name does not search in the embedded links. Also note that wildcards
* are supported in SE's built-in search.