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Strange editor
Please look at these edits: Special:Contributions/Hanumantw; not vandalism, but... something strange? Boris Tsirelson (talk) 16:07, 11 August 2019 (UTC)
- It may not be deliberate destruction motivated by hatred of the good, but damaging things as a result of carelessness or ignorance can be just as harmful. JRSpriggs (talk) 01:21, 12 August 2019 (UTC)
- Now blocked indefinitely. Boris Tsirelson (talk) 08:15, 17 August 2019 (UTC)
Australian IP edit-wars in Quaternion
Insists that knows the only correct notation and the rest of the world the preceding version is “wrong”. Look at https://en.wikipedia.org/search/?title=Quaternion&action=history&offset=2019081216&limit=9 and talk:Quaternion #Exponential, logarithm, and power functions, please. Incnis Mrsi (talk) 15:42, 12 August 2019 (UTC)
Very depressing bug in the editor
I was editing Talk:Axiom of union#Independence of the axiom of union. I had planned out what I wanted to say in my head and was rushing to get it committed to writing before I forgot it. As usual, there were times when I needed to look at another article to get the correct spelling or latex symbol. This time, I went to the Axiom of powerset to get the symbol for the powerset. I had to enter the editor to see the source of that article to get "\mathcal (P)". When I tried to back out of that edit and return to my original edit, it would not allow me to do so. Ultimately, I had to "resend" to escape and as a result I lost most of what I had already written. I cannot say in words just how discouraging this is. For several minutes I sat stunned, enervated, unable to do anything. Eventually, I forced myself to re-enter an approximation to what I had written before.
This is not the first time this has happened. It has happened several times before. But it is infrequent enough that I forget to take precautions against it. Is there some way to get this bug fixed? JRSpriggs (talk) 01:20, 13 August 2019 (UTC)
- Which editor(s) are you using? It may make a difference. I haven't had problems except when my browser exceeded available memory on my machine and locked up.... 01:36, 13 August 2019 (UTC)
- (edit conflict × how ironic) Not quite sure I'm following your steps exactly. Do you mean that from the edit window, you went directly to another article (maybe via the search bar), and then hit the back button on your browser only to find that it hadn't saved the state of what you were doing? If so, then that's not really a bug; there's no guarantee that a browser will keep the current state of what you're doing cached if you move forward to another page. Ideally it will try to, especially for simple stuff, but that's not something you can rely on. On the other hand, if you go browsing in another tab or window, then all should be fine, but if not, it's likely browser-related, not a Mediawiki issue. Or have I misunderstood what the problem is? –Deacon Vorbis (carbon • videos) 01:42, 13 August 2019 (UTC)
- To Arthur Rubin: I was just using the normal editor provided by Misplaced Pages, the old one, not the visual editor.
- To Deacon Vorbis: Yes, I think you got it right. My browser is Firefox. I was thinking that there are three things I might do to work around this: (1) copy the source of my edit into a file on my disk before going on such expeditions, just in case this happens; (2) do the search and cutting (before pasting) in another copy of Firefox; or (3) save my edit before I am really done and then edit again after I have done the search. What do you recommend? JRSpriggs (talk) 06:13, 13 August 2019 (UTC)
- This depends on the browser, and even on the browser version. With Safari, non-saved edits are sometime lost, sometime not lost when one come back to a page with the back button. If one has left the page after clicking "show preview", edits are sometimes kept, but with the most recent versions they are kept only if one does almost nothing (no search in the page, no diff, no look to the source, ...) with the visited page(s). Therefore, I have now the habit to use another tab for navigation during an editing process, and, when searching or following a link from the edit window, to to it with the right button and "open the link in another tab". D.Lazard (talk) 07:51, 13 August 2019 (UTC)
- That's more or less my habit as well. XOR'easter (talk) 15:22, 13 August 2019 (UTC)
- To Lazard: Thanks for the suggestion. I will try the right-click on a link to get a separate tab method. JRSpriggs (talk) 01:29, 14 August 2019 (UTC)
- That's more or less my habit as well. XOR'easter (talk) 15:22, 13 August 2019 (UTC)
- This depends on the browser, and even on the browser version. With Safari, non-saved edits are sometime lost, sometime not lost when one come back to a page with the back button. If one has left the page after clicking "show preview", edits are sometimes kept, but with the most recent versions they are kept only if one does almost nothing (no search in the page, no diff, no look to the source, ...) with the visited page(s). Therefore, I have now the habit to use another tab for navigation during an editing process, and, when searching or following a link from the edit window, to to it with the right button and "open the link in another tab". D.Lazard (talk) 07:51, 13 August 2019 (UTC)
- I’m late but I can confirm I had the same type of (very disheartening) experiences before on multiple occasions; they may have been in Misplaced Pages or some other website. Since I couldn’t figure out the behavior (how unsubmitted text is handled), my habit has been to copy large text into the clipboard before hitting submit (if edits are small, I don’t bother). —- Taku (talk) 22:54, 17 August 2019 (UTC)
Factorial and double exponential
See recent history of factorial. An editor there insists that the constant function f(x)=1 is an example of a double exponential function and on using that example to change the statement that the factorial grows "slower than double exponential functions" to the overly-pedantic "slower than many double exponential functions e.g. (example)". I don't think this is an improvement, but additional opinions might be more helpful than my repeated reversion of these edits. —David Eppstein (talk) 22:46, 17 August 2019 (UTC)
Puzzled by watchlist
This WPM talk page is on my watchlist, in the sense that I do see the corresponding blue star between "View history" and "More". And nevertheless it does not appear on my watchlist. This is a new phenomenon (the last week or two). Mostly, my watchlist looks as before; but some items are missing, I do not know why. If I click the blue star ("remove this page from your watchlist") and then click the (no more blue) start again (making it blue again), it helps; the page returns to my watchlist. But afterward it disappears again. Why so? Boris Tsirelson (talk) 06:51, 19 August 2019 (UTC)
Or maybe not quite so. I just tried to click twice the star on Talk:Normal distribution (edited by me yesterday, and by a bot today); it did not help. Boris Tsirelson (talk) 06:57, 19 August 2019 (UTC)
Empty square root
The empty square root generated as <math>\sqrt{\;}</math> is very badly aligned (I have found this in nth root). The reason seems that the alignment is done on the center of the argument and that the space character is viewed as a zero-height character placed at the bottom of the line. For having a normal alignment such as I have used <math>\sqrt{{~^~}^~\!\!}</math>. Do someone know a less weird method for a similar result? D.Lazard (talk) 07:42, 19 August 2019 (UTC)
generated as <math>\sqrt{\;}</math> is very badly aligned (I have found this in 
I have used <math>\sqrt{{~^~}^~\!\!}</math>. Do someone know a less weird method for a similar result? - P.S. A similar result () is obtained with <math>\sqrt{\color{white}{x}}</math>, but it is also semantically doubtful. D.Lazard (talk) 07:54, 19 August 2019 (UTC)
- Try <math>\surd</math>, giving . No horizontal bar, but it does better align it with the text. If WP handled real TeX, \sqrt{\phantom{x}} or \sqrt{\hspace{1em}} would be reasonable ways to create an empty square root.--
{{u|Mark viking}} {Talk}08:14, 19 August 2019 (UTC)
- Try <math>\surd</math>, giving . No horizontal bar, but it does better align it with the text. If WP handled real TeX, \sqrt{\phantom{x}} or \sqrt{\hspace{1em}} would be reasonable ways to create an empty square root.--
) is obtained with <math>\sqrt{\color{white}{x}}</math>, but it is also semantically doubtful. 
. No horizontal bar, but it does better align it with the text. If WP handled real TeX, \sqrt{\phantom{x}} or \sqrt{\hspace{1em}} would be reasonable ways to create an empty square root.--Convex hull lower bound
Please see Talk:Convex_hull_algorithms#Lower_bound_on_computational_complexity --GunterS (talk) 08:43, 21 August 2019 (UTC)
- Already answered there. D.Lazard (talk) 09:21, 21 August 2019 (UTC)
Cocycle of a group action
It is a pity that cocycle of a group action is not treated; neither in "Cocycle", nor in "Group action (mathematics)". See Talk:Cocycle#Cocycle of a group action. Boris Tsirelson (talk) 08:22, 24 August 2019 (UTC)
Pollard algorithms
Are Pollard's rho algorithm for logarithms and Pollard's kangaroo algorithm about the same thing? Bubba73 15:35, 24 August 2019 (UTC)
- I am not acquainted with these; but in "Pollard's kangaroo algorithm" I read: "Pollard's kangaroo algorithm ... introduced ... in the same paper as his better-known Pollard's rho algorithm"; if so, then they are two different algorithms "for solving the same problem". Boris Tsirelson (talk) 17:21, 24 August 2019 (UTC)
- The way it seems to me is that Pollard's rho algorithm is for factoring numbers and the other two use a similar method for finding discrete logarithms. Bubba73 18:09, 24 August 2019 (UTC)
Draft:Genus of a group
Is this a topic that deserves a separate article? Genus (mathematics)#Graph theory already covers the topic but a quick Google search shows the topic is of independent interest. (I admit I’m not a specialist on this area so the others might know better.) — Taku (talk) 22:52, 26 August 2019 (UTC)
- No separate IMHO, but definitely as little as redirect to Cayley graph
, especially because the article already mentions the genus of it (albeit without a wiki link). Incnis Mrsi (talk) 16:21, 27 August 2019 (UTC)- Where in Cayley graph is the genus of a Cayley graph discussed? --JBL (talk) 17:09, 27 August 2019 (UTC)
- In fact, nowhere the genus of the graph (I suffered a glitch). Anyway the concept is defined via Cayley graphs and may deserve a section there. Incnis Mrsi (talk) 17:24, 27 August 2019 (UTC)
- I'd start by writing about the concept at Cayley graph and then breaking it out into its own article if that material grows too big. XOR'easter (talk) 17:45, 27 August 2019 (UTC)
- In fact, nowhere the genus of the graph (I suffered a glitch). Anyway the concept is defined via Cayley graphs and may deserve a section there. Incnis Mrsi (talk) 17:24, 27 August 2019 (UTC)
- Where in Cayley graph is the genus of a Cayley graph discussed? --JBL (talk) 17:09, 27 August 2019 (UTC)
A question about English grammar
The article titled Nonlocal operator begins like this:
In mathematics, a nonlocal operator is a mapping which maps functions on a topological space to functions, in such a way that the value of the output function at a given point cannot be determined solely from the values of the input function in any neighbourhood of any point. An example of a nonlocal operator is the Fourier transform.
Occasionally I think English-speaking mathematicians are not attentive enough to nuances of the use of the word any.
-
- This function can take any number as an input.
is not quite the same as
- This function can take every number as an input.
since in some contexts this might mean every number at the same time. But
- Any function from R into whatever is blah blah blah.
means
- Every function from R into whatever is blah blah blah.
Maybe this point is clearer if one thinks of the difference between "Any member can preside over this meeting." and "Every member can preside over this meeting."
But suppose you say
- If it is the case that any function from R into whatever is blah blah blah then etc.etc.
That is in danger of being read as
- If any function from R into whatever is blah blah blah then etc.etc.
and hence as
- If there is any function from R into whatever is blah blah blah then etc.etc.
so that a universal quantifier in the writer's mind becomes an existential quantifier in the reader's mind. Merely writing "every" instead of "any" at the outset is all it takes to obviate this hazard.
Thus "any" can be universal in some contexts ("Anyone can do that.") and existential in others ("There isn't any." or "If anyone can run a 50 meters in three seconds, it's Usain Bolt.") The contexts in which it becomes existential seem to be these:
- Negative sentences: "I've never seen any examples of that."
- Questions: "Is there any money left?"
- Conditional clauses: "If there is any money left, donate it to Misplaced Pages."
How shall we apply this to the two occurrence of the word any in the passage quoted from Nonlocal operator? Michael Hardy (talk) 18:25, 27 August 2019 (UTC)