@joyal
In the list of contributors on the CatLab you have one 'Robert, David'. I hazard a guess that this is me, but there may be a David Robert out there that I haven't heard of. If this is me, shall I change it, and can I make a rudimentary page which just points to my nLab page?
]]>Here is how to do it:
click on the link "History" at the very bottom of the page.
you'll be led to a page that lists all the different versions of the entry. Click on the one that you want to get back to.
Then when you see the page with the version you want, go again to the bottom and click on "Rollback". That will open the edit window as usual, but now with that version's source code.
Hit "submit" to save this as the latest version.
I have found the answer to my question: I just rool back. Sorry for disturbing you.
]]>I am presently writing a page in the Catlab on model structures on the category Cat but I have messed up everything by pressing the wrong keys. I would like to return to verson 24 of the page. How can I do that ? Thanks.
]]>It's worth making clear that the SVG editor does not originate with Jacques (though he is now allowed to commit code to the project) and he's not (unlike Instiki) intending to take it over (as far as I know). He's mainly focussing on making it work well with Instiki, and so his main focus is getting it to play nicely with itex. Stuff like having a grid has more of a feel of a suggestion that should be made to the main developers (who, I'm sure, would love to hear from people using their software!).
There is a crude way of doing what you say: it's possible to edit the co-ordinates for stuff directly, so you can put the stuff roughly in the right places and then line them up manually.
]]>It would be nice if he could add a grid to it so we could arrange things more easily.
Edit: And apparently Andrew does have the abilities I doubted anyone here would have. Oh me of little faith. =)
]]>Well, a crude way of automating it would be to pass the xy code through PHPLaTeX to generate a reasonable approximation of the SVG and then edit that in the editor to make it actually look nice. Or I could take a little time to clean up the SVG produced by PHPLaTeX (there's a few things that I know now that I didn't know last year when I wrote it) and then it would probably work okay on most xy diagrams without modification.
But Jacques has a few more ideas about the SVG editor so I'm holding back on the mass conversion until those settle down. This was more in the way of advance warning!
]]>@Urs: I really really doubt it. I think codecogs takes the LaTeX, generates the diagram then "takes a picture". To somehow write that into SVG would essentially be "convert xypic stuff to SVG". It could be done (maybe even should be), but I can't see it being easy, and it's probably beyond our abilities to do it (unless any of you has secret programming skills that I'm not aware of [I know I don't!]).
]]>I will be converting all the codecogs diagrams to SVGs using the SVG-Editor that Jacques has installed. The only real reason I haven't done so so far is time
Any chance that the process could be automated?
]]>Maybe there is a way that we buy the software or someting and install it on the nLab server itself.
I'm letting people get away with using codecogs for the moment, but I should warn you that on the nLab, I will be converting all the codecogs diagrams to SVGs using the SVG-Editor that Jacques has installed. The only real reason I haven't done so so far is time (and wanting to get a few bugs ironed out first). It really is impressive and it has the Killer Feature in that one can edit an existing diagram.
But depending on another site for serving part of the nLab is something I'd really like to get rid of. This just explains why.
]]>it seems to me that the CodeCogs server that generates the diagrams is down.
I just checked explicitly on their own equation editor webpage (here). While that page itself is available, it does not disyplay any equations/diagrams at the moment.
I think at the moment all we can do is wait a bit until they have restarted their equation server. In the long run we might maybe want to contact the people who run this software. Maybe there is a way that we buy the software or someting and install it on the nLab server itself.
]]>Is there a problem with the computer system? I was not able to compile new diagrams today. Also, compiling is very sluguish.
]]>This was my stupid mistake! My eyes are not good anymore. Thanks.
]]>The closing 'center' tag wasn't right. In the second square you had '<center>' but it should have been '</center>'. Changing it made it work (see Sandbox (joyalscatlab)).
(Incidentally, you can link to pages in your web from here using the double-square-bracket notation. Type 'joyalscatlab:Sandbox' surrounded by double square brackets to make the link. If pasting in a URL as you do above, you should paste in the "show" URL, not the "edit" one - then there's no risk of people accidentally editing your page.)
]]>@Andrew: This was very helpful. It works. Thanks!
I found something quite bizarre: I have reproduced two squares of objects and arrows in my Sandbox:
http://ncatlab.org/joyalscatlab/edit/Sandbox
The squares were first created in my page
http://ncatlab.org/joyalscatlab/edit/Weak+factorisation+systems
The system is refusing to compile the second, while it is accepting the first. But they look syntaxically identical to me! Beware that the second square was not obtained by copying the first. They differ by their history, their life line. The second guy was a problem from birth. A copy of the bad guy is bad and a copy of the good guy is good. Why is that? Equality is evil?
]]>I've had a look and I have a solution for you. It perhaps is not the most elegant method, but it does work.
When using square brackets for displayed equations then the opening bracket has to appear at the start of a line (you can have a little whitespace in front, but not too much). That's the first thing to note. The second thing is that if the mathematics is empty, then the label is still produced but gets attached to the next line (in particular, you don't get a blank line with a label at the tend). This is good because it means that we can attach the label to the next line, which consists of the diagram - I tried embedding the diagram in the equation environment but it didn't like that.
So what I propose is that you do:
\[\label{foo}\]
<center>
<img src="whatever your picture is">
</center>
Then the equation number appears next to the diagram. Admittedly, it is aligned with the top of the diagram rather than the usual LaTeX standard of the middle. However, that is actually beneficial since it means that someone clicking on the link to jump to that diagram can see the whole diagram straight away without having to scroll.
Refer back to it via \eqref{foo}
or (eq:foo)
as I said above. I've put this in on Weak+factorization+systems (joyalscatlab) at the end of proof 1 of proposition 3 - I hope I got the right diagram! - so you can see from that example how to use it.
Hope that helps!
]]>I'll take a look tomorrow.
]]>Dear Andrew,
I have followed your instruction without success. When I compile
\eqref{abc} or (eq:abc)
the system reacts by returning a blank page with an error message. I must be doing something wrong. I will be grateful if you could fix the problem for me. --André
]]>Equations can be given anchors by using \[
and \]
instead of double dollars, and then put \label{foo}
inside the delimiters to create a label. Refer back to this either via (eq:foo)
or \eqref{foo}
.
(If you want to refer to an equation on a different page then it'll be something like the [text](link)
syntax but I'll need to do a modicum of investigating to figure out exactly what to put where and I've not time to do that right now.)
If you put your diagram inside an equation, then you can refer to it like this. If your diagram is by itself, then there's a few different ways depending on exactly how the diagram is placed. Again, to be absolutely sure of the syntax I'll need to do a couple of experiments to see what is correct. If it's alright by you, I'll try to fix the references that you mention above and that'll tell me what the correct general syntax is - but it'll be tomorrow at the earliest. Rest assured that it can be done, and fairly easily, but I want to be sure that I've got it right.
]]>@Stacey: I understand my error. I corrected it and it now works. Thanks.
Another technical problem: I sometime would like to refer to a diagram in a proof but I do not know how to label the diagram (see for example the end of proof 1 of Proposition 3 in
http://ncatlab.org/joyalscatlab/show/Weak+factorisation+systems)
where are refer to an unlabelled square. Can you tell me how to label diagrams (and equations)?
]]>The anchors need to be attached to something, they can't hang in midair. So either add a (sub)section header where you want an anchor, or link directly to the lemma. That particular lemma has reference 'cancelquasicartesian' so link to that instead:
[here](http://ncatlab.org/joyalscatlab/show/Epicartesian+squares#cancelquasicartesian)
(You're editing the page at the moment, otherwise I would have corrected it for you.)
]]>The informations in the Sandbox are good enough for me, except those about the WYSIWYG SVG editor, but it does not matter at the moment. I keep worrying about link-references. The anchor technique is unprecise. For example, the link here in the Proof 2 of Proposition 3 of
http://ncatlab.org/joyalscatlab/show/Weak+factorisation+systems
is taking me at the top of the page and not to Lemma 4 as intended. This can be very disorienting. Am I doing something wrong?
]]>@Joyal: Please let us know which examples are good to learn from and which aren't - we'll transfer the good ones to the HowTo as the Sandbox can get wiped clean from time to time. And if there's something you can't figure out, drop a line here and one of the lab elves can have a look at the page in question and sort it out for you.
@Mike: well, it doesn't quite pass it blindfold - it checks for nasty stuff, but the point of the [text](link)
syntax is to form links to other pages anywhere in the web. Instiki doesn't check to see if they happen to be actually on the nLab.
Yes, one may link-refer to a dynamically numbered proposition, but the number will not be shown on the referring page; all you can do is make a link. I showed it at the Sandbox and also mentioned it at the HowTo.
@Andrew: Ah, I see. I didn't realize that instiki was just passing whatever is in the (...) of a [link](...)
verbatim to the html anchor tag.