Richards asks that we report bugs in a single thread, and if discussion is needed start a new thread for each.
]]>A few people have noticed that nLab pages rendered by Firefox sometimes leave out some math symbols. This can be annoying but can be fixed by reloading the page.
This happened to me today when I opened functoriality of categories of presheaves. That page should have 2 MathML expressions near the top which should be rendered as “” and “”. Today they were rendered as “” and “” except that their layout was more like room had been reserved for the missing characters which were just invisible. I decided to right click on one of those and use the inspector to see what Firefox was trying to render. But when I did and the inspector panel came up both items became correctly rendered.
I think this means that there is some sort of rendering timing bug in FF that makes it think it has fully rendered characters when it hasn’t, and it is no fault of the nLab page source or any extensions installed.
I don’t know how to get Mozilla to address this usually not repeatable bug.
Firefox version: 122.0.1, Windows 10 version: 22H2 19045.4046
]]>Since about two weeks now, we have full-server backups – automatically built and quickly deployable.
Let’s stress-test the temporary test deployment to gauge availability of all features:
Occasionally you might be redirected to the true nLab or the true nForum, that it is to be expected, but feel free to report such issues here.
]]>In our displayed-math environments various “operators” (such as “\prod
” “\coprod
” and “\int
”) are typeset in a fontsize that seems too large.
For instance “\coprod_i X_i
” gives (in display-math style)
or “\int_x f(x)
” gives
which in general seems excessive in vertical size.
Now for “\coprod
” there is the alternative “\amalg
”
which is more often the size one really wants. Of course there is also “\sqcup
”
but it’s look is not so great for a general coproduct and also this is now getting too small.
My question really is: Do we have (in Instiki) an analogous alternative for “\prod
” (as “\amalg
” is for “\coprod
”)?
I am aware of “\sqcap
”
but I’d rather have the upside-down version of “\amalg
”, instead. If it exists?
(I have stared at the list of Instiki symbols, but it’s hard to penetrate.)
]]>Is there a syntax for comments in the Instiki source code? Some way to include text into an nLab entry source that gets completely ignored when rendering the page?
]]>Has the way math displays are rendered been changed recently? I have been getting little vertical scrollbars next to displays when viewing in chrome lately, and in firefox displays also look very cramped, at least in itemized lists. See eg final functor. Or maybe it’s a change in chrome and am only imagining the change in firefox?
]]>The single most important thing for the protection of the nLab against a ’disaster’ is that we have regular backups of the database in different locations. Nowadays a lot of systems would do this in the cloud, but we can achieve something more or less as good if people are willing to volunteer to regularly download a backup.
An item on the Technical TODO list (nlabmeta), 20 currently, has been to make this possible technically. Prompted by the fact that Jake is making preparations for working on the nLab frontend and needed this, I have now done this (there is now a password protected endpoint one can call to generate an SQL dump and download it).
My question is: would some people be willing to make the downloads regularly (as many as possible!)? And what would be most convenient for you? A user interface where one clicks a button? A script which you run on your own machine? Something like a cron job which runs the script once a day, or week, or whatever on your own machine?
]]>This may be an issue with my version of the hyperref package, or something else unique to me, but the bib entry for the “reflected limit” page causes errors if directly copied and pasted into a bib file because there is no backslash before the “%” symbol. I haven’t checked the suggested citation entry for every nlab article, but it seems to effect everything with more than one word in the title: the “+” converts to “%20” when it should convert to “\%20.”
]]>This to announce that the technical team is going ahead with the migration of the nLab installation to a new server:
The migration will take place this Friday (7 Oct, 2022) at 15 CET / 13 UTC.
They will start by switching the nLab and nForum to read-only. During this time, you will get an error message if you try to edit or post in the nForum.
At the end of the migration, they will point the nLab and nForum to the new server and editing/posting will work again.
It may be that some things are broken afterwards. If you notice any, please post them here!
The nLab and nForum codebases suffer from the design flaw that database timestamps are stored in local time without timezone annotation. From the switch to saunders on 2015-05-16, the server has been running on America/New_York (with ambiguous times during DST transition). We are still investigating local server time before that, but at least in 2015 before the switch to saunders, the server used UTC.
To work around the evident problems, we will migrate the server and database timestamps (at least from 2015) to UTC. While this is happening, the nLab and nForum will be switched to read-only mode. The migration will start after 22:30 UTC today and last for less than an hour. We will announce the start and end of the migration in this thread.
]]>I have finally completed an initial implementation of something I have long been planning (I began over 2 years ago!), and which has long been wished for: a proper referencing mechanism for the nLab.
It is far from complete, but the basics are there, and it can be taken into use immediately. I have given an example in the current version of the Sandbox of how to use \cite
and \bibitem
for items that have already been added to the central nLab bibliography. To add a new reference to the bibliography, one does the same kind of thing as for creating a page, etc: one just writes \bibitem{MyExpectedCitationKey}
on the page, it will show up as MyExpectedCitationKey?
when you render, and the ?
is a link to the page for creation. After you save the reference, you will be taken to a little page which displays the reference, which can also be viewed directly at /nlab/reference/show/MyCitationKey
. For example, the two references I have added can be viewed here and here.
I think we would all agree that the value of having a central bibliography rather than referencing on individual pages is potentially considerable, so I hope people will take this into use! The idea is that \cite
and \bibitem
should essentially reproduce what is typically done by hand currently.
I have had to make some choices along the way. For example, a ’citation key’ is generated from the bibliography entry. It follows the rule: concatenation of surnames of all authors plus year. It is not perfect, and I am open to suggestions, but it should be OK for now, and is similar to what we currently do. To get this to work well, it is important that the author field of the bibliography entry is entered in a certain format. This is explained in the instructions on the reference creation page. Links to nLab pages are allowed.
You will see that I suggest to create a bibliography entry by fetching a BibTex entry from Zentralblatt and pasting it in, modifying the author field. Zentralblatt has always been openly available with some search restrictions, but since this year is now completely open. Thus I think we should use it rather than MathSciNet, and should ideally not use home-grown BibTex files, although there is little that can be done to stop this currently (it is not a disaster if people do this, but having a canonical source is preferable). Zentralblatt plan to create APIs for interaction with their data, which would probably be very useful for us in the future.
Currently I have only implemented rendering of ’article’ type BibTex entries! Obviously I will implement the other most common types asap, but ’article’ should be enough for people to try things out. Again, I have followed how Zentralblatt styles the rendering, but I am open to other ways to do it. There are a million other things we can later do with this, e.g. generate the references rather than manually typing ’bibitem’, but it’s a start. One thing we will definitely need is some kind of search functionality for bibliography, or at least (to begin with) a list of the entire bibliography. Again, I will add something like this soon. Also editing of references will be needed. Maybe they should be announced at the nForum when created/edited. Etc.
]]>I tried to edit the entry double derivation and even if I write a single letter or none (!) it sends back an error
500 Internal Server Error
Your edit was blocked by spam filtering
Please report this on the nForum in the nLab Technical Matters category. Please give as precise details as you can as to what triggered the error.
nLab home page
Here is the error:
No such file or directory @ rb_sysopen - page_content/submitted_edits/nlab/double_derivation
etc. If I try to click on “discuss” button it does NOT open the latest changes page but just links to front page of Forum, not linked to a page.
]]>Meanwhile, Christian Sattler and Felix Cherubini (from the technical team) have installed a copy of the nLab+nForum system on our new server. The idea is to migrate to that server, but now first to stress-test the new installation, in order to discover remaining glitches and other issues.
For that purpose we are hereby kindly asking everyone interested to play with the new installation and see if anything seems off.
The mock-up new nLab is at: http://saunders2.andrew.cmu.edu:8008/nlab
The mock-up new nForum is at: http://saunders2.andrew.cmu.edu:8009
The idea is to stress-test all the functionality (e.g. typesetting, redirects, edit announcement, file upload, !include
files – whatever you can think of). We already did such testing, but best to catch any remaining bugs before the new installation goes live.
If you join in the testing, please beware of these two points:
All nForum-passwords on the mock-up nForum have been set to “nforum2022
”. Be careful not to use your real password when logging into the test-nforum at the above url. Because there is no https yet, any password you use will be sent in plain text.
No link in the mock-up installation should be directing to the real nLab – but please look out for this and report as a bug if it does happen nevertheless.
Thanks for everyone’s help with this! And a million thanks to Christian, Felix and the other members of the technical team for making it happen.
]]>Probably the topic says it all: Is there a way how to convert nLab pages into a PDF, where all the links to other parts of the same site are retained, while external links don‘t need to be clickable. For context, I am trying to effectively download some of the lecture notes that are stored on the page.
]]>I’ve edited the page “differential category” and added an hyperlink to “Graded differential category” that I wanted to create after. Now, the page “differential category” collapsed and there is an error displayed when you try to access it…
Do you know how to solve this issue and what did I do wrong?
]]>I just tried to see the difference between the most recent versions of Heyting algebra.
Instead I was taken to editing that page. Closing that tab left the page locked by me, so I had to force re-editing anyway and cancel my edit.
This link causes the problem https://ncatlab.org/nlab/show/diff/Heyting+algebra.
Trying a diff between earlier versions gives a 500 Internal Server Error.
]]>Just a heads-up that an unprecendented number of silent edits signed by “Anonymous” is occurring all over the nLab, and has been over the last days and weeks. I was trying to keep up with cleaning up after some of them, but it’s a flood and I am being overwhelmed.
For example, the entry unvalence axiom was substantially edited yesterday (rev 68) without any notification. The edit is something that could potentially be useful, but like similar such Anonymous edits it appears rather oblivious to the general logic of pages.
This would all be fine if the user(s) making these edits would be reacting to comments and taking advice and suggestions. But I am getting the impression they might not even be aware of the existence of the nForum, or otherwise choose to ignore it.
I am talking with the technical team about this. If these Anonymous users do not come out and become responsive, we may need think about altering the way users may edit pages.
]]>Prompted by signs that the current server is reaching its limits with the existing software, I am going to attempt to carry out the migration to the cloud (Amazon Web Services, aka AWS), that has been intended since we raised funds for this purpose early this year. For those who do not remember, we will be using an AWS account owned by (and billed to) the Topos Institute. Brendan Fong is our principal contact at the Topos Institute.
The full migration will take a long time. I do not really have time for it myself at the moment, but the time has come that it is necessary to do something. I am going to try to gradually build functionality up; the first goal is simply for the nLab to be viewable (i.e. it will exist in read-only mode to begin with).
I am now going to disable the current nLab server, to prevent writes to the database whilst I am migrating existing content. My apologies for the inconvenience, but with the tiny amount of time that I have, this is the only simple way to do things cleanly.
I hope to be able to get read-only mode up this evening European time; I will keep you updated. The nForum will remain up.
PS - This is not just a question of moving the software over. The old/original Instiki will be completely gone once the migration is complete. The nLab should look the same/similar on the surface, but the only traces of the original code will be the CSS.
]]>This is new: when trying to save an addition to the entry Chern-Simons theory I get the message
Your edit was blocked by spam filtering
In case anyone else can more successfully pretend not to be a spammer and wants to help, this here is what I was about to add to the References-section, at the end of “With Wilson loops and defects”:
Discussion of boundaries (branes) and suface defects for Chern-Simons theory is in
Anton Kapustin, Natalia Saulina, Surface operators in 3d TFT and 2d Rational CFT in Hisham Sati, Urs Schreiber (eds.) Mathematical Foundations of Quantum Field and Perturbative String Theory (schreiber) AMS, 2011 {#KapustinSaulina11}
Anton Kapustin, Natalia Saulina, Bicategories for boundary conditions and for surface defects in 3-d TFT, Nucl.Phys.B845:393-435,2011 (arXiv:1203.4568) {#KapustinSaulina12}
Jürgen Fuchs, Christoph Schweigert, Alessandro Valentino, Bicategories for boundary conditions and for surface defects in 3-d TFT, Hamburger Beitr. zur Mathematik Nr. 433, ZMP-HH/12-5 {#FSV}
It is high time that we put the donated funds to use for securing the physical existence of the nLab installation.
We still need to urgently migrate the installation to a new server (the one we are running on had been sunsetted already years ago) and then we need to possibly hire a sysadmin to take care of the day-to-day operation of software and server.
For these and related IT tasks, we need a body of technical experts who can make informed decisions about how to use the donated funds for the purpose of guaranteeing the hardware & software existence of the nlab, such that the Topos Institute – which is kindly administering our funds for us – can rely on their expressed decision when paying bills for us.
For this purpose has now been created a body called the nLab technical board.
The founding members of the technical board currently are:
Adeel, Felix and Mike are currently the three persons who have the password to the nLab server, know what it takes to do there and have been doing it and are doing it. They are the ones keeping the nLab in physical existence at the moment.
You all know Mike, he is in particular the one founding member of the nLab community who is IT-savvy enough to serve on such a board.
Adeel, to recall, is our pre-previous admin who two weeks ago suddenly jumped in and revived our running installation by pointing the DNS server back to it.
Felix had migrated the nLab to a secure server already a year ago, but then we didn’t go live with it as we still trusted somebody else would do this (and now that server has been decommissioned, unfortunately). Incidentally, a week ago Felix figured out what it was that kept the nLab running slow – turns out it was a broken backup mechanism that apparently broke back in 2018. He fixed it right away. The nLab is much more responsive now, you will notice when you do editing. And it’s again being automatically backed up now.
These three kindly agreed to help us out by lending their names to the “nLab technical board” and by taking care of organizing the next steps that need to be taken with the nLab’s installation and authorizing required payments.
In fact, since a few days ago, a further volunteer has kindly joined in and started helping with detecting problems in the current installation.
Similarly, if you are a technical expert on the required IT issues and would like to lend a hand with keeping the nLab installation alive and well, then please drop a note, either here or directly to one of the technical board members. (You don’t have to become a formal member of the “technical board”.)
]]>The nLab and nForum were both down today from around 08:00 CET to a little before 16:00 CET. The entire server at CMU which hosts both was unresponsive. No details yet on what happened, I’ll update once I know more.
]]>