(By the way, I have to say that I honestly do not see what exactly is 'visual-math' supposed to be, looking at what he has tagged...)

Oh, for the love of Om...

Fair point Mariano. I was not intending to remove all of them, but my hope was that by removing one or two I could get JB to contact me - I can't find an email address on his profile or weblog or via Google. But as you say this is best left to the Powers That Be. (Who force us to live like we do.)

Harry: well, as I may have said at the time, I don't like the fact that a moderator's vote to close is final (as it were). Also, at the time I said I should be spending less time on MO, and that is certainly true - I'm only on at the moment because I can't get a calculation to come out right...

I think that many of the questions Jose tagged as [visual-math] should not be tagged as such. Here's my list:

http://mathoverflow.net/questions/24737/the-upper-hat-of-an-octahedral-diagram-in-latex
http://mathoverflow.net/questions/25983/intuitive-crutches-for-higher-dimensional-thinking
http://mathoverflow.net/questions/26939/geometric-imagination-of-differential-forms
http://mathoverflow.net/questions/24453/how-does-singular-homology-h-n-capture-the-number-of-n-dimensional-holes-in-a-s
http://mathoverflow.net/questions/21424/how-to-draw-knots-with-latex
http://mathoverflow.net/questions/21024/what-is-the-exterior-derivative-intuitively
http://mathoverflow.net/questions/20847/why-are-the-dynkin-diagrams-e6-e7-and-e8-always-drawn-the-way-they-are-drawn
http://mathoverflow.net/questions/18758/drawing-a-combinatorial-3-configuration-of-points-and-lines-with-pseudolines
http://mathoverflow.net/questions/15600/how-to-fill-a-simplex-with-almost-disjoint-cuboids
http://mathoverflow.net/questions/17635/drawing-3-configurations-of-points-and-lines-with-straight-lines
http://mathoverflow.net/questions/15322/visualizing-whats-going-on-in-based-homotopy-theory-et-al
http://mathoverflow.net/questions/11743/database-of-polyhedra
http://mathoverflow.net/questions/9991/how-can-i-sample-uniformly-from-a-surface
http://mathoverflow.net/questions/7859/how-to-teach-addition-of-negative-numbers-closed
http://mathoverflow.net/questions/6810/seifert-surfaces-of-torus-knots
http://mathoverflow.net/questions/5936/whats-so-great-about-blackboards-closed
http://mathoverflow.net/questions/5133/how-to-present-overlap-of-related-sets-closed
http://mathoverflow.net/questions/2692/matrices-into-path-algebras
http://mathoverflow.net/questions/1977/why-is-the-gradient-normal
http://mathoverflow.net/questions/1194/how-to-partition-r3-into-pairwise-non-parallel-lines

This is so extensive that my preferred option would just be to merge [visual-math] into [tag-removed], unless we can convince Jose to roll these back himself.

[Post is now irrelevant]

First: thanks Jose for coming over to this thread to discuss this.

I guess my problem is that, as I see it, almost any question in mathematics can be thought of in visual terms, at least in part, since that seems to exploit a well-evolved part of our neurological setup/training. Should I start tagging functional-analysis questions with "visual-math" just because I'm thinking about block bases or "compact operators squashing regions" or "isometries" moving "mass" far away? How about probability questions where people are thinking of a Brownian motion meandering its way out of a given region?

I just fear that as conceived, the tag just applies too broadly, and if it is to stay it should really be used for questions specifically asking for aids to visualization.

@Yemon:

Thanks for raising the issue!

I agree with you in that visualizing is a "brain-imprinted" skill and can appear de facto everywhere in mathematics. But, if you look closely at the questions I tagged, they are 'specifically asking for aids to visualization' (or, at least, that was my intention), although they do not necessarily mention the word 'visualization' (but they ask for drawings, graphics, figures, and the sort). For example, in the first question listed by Scott, http://mathoverflow.net/questions/24737/the-upper-hat-of-an-octahedral-diagram-in-latex, someone wanted some aid in getting a good visualization for an octahedral diagram via latex.

I hope the problem is more with the site upgrading the questions rather than with the tag itself (of course, taking its name apart: I recognize it may be a bit misleading); at least I hope to somewhat convince you, since, for me, that tag (perhaps with a better name) would we useful.

Yemon, with that tag I do not intended to include what is usually understood by 'visualization' in mathematics: that's a really broad concept, as you already pointed very well! That's precisely why I did decide to call it "visual-math" instead of some combination of words with 'visualization' on it. With 'visual' I refer to the usual, most specific meaning of the term: simply something that you could draw and look at (to aid you or to solve your problem).

In the nice example you propose, I definitely WON'T add the "visual-math" tag to your question, unless you specifically said somewhere inbetween: "I'd like to find some asymptotic bounds on this sum, and it would be cool if we could do it , or at least approximate them, just by having a look at the right Hasse diagram. Any clues?" (So that I will infere that you indeed want or are in the need of using a visual tool).

Any tag needed so much explanation is probably not very useful to the masses... :P

Continuing the discussion of individual questions:

I strongly agree with Yemon that my first example about the octahedral example has nothing to do with visualization, it's purely asking how to render a diagram in LaTeX.

I actually went through the list of all the questions you tagged, and I have specific reasons for opposing the [visual-math] tag on each question on my list, and I think it's fine and appropriate on the complement! Perhaps you should try defending others from my list, Jose, so we can come to an agreement about the scope of the tag?

For what it's worth, I agree with Kevin Lin -- many, many questions on MO could be concerned with visualization if one is inclined to construe them that way. It doesn't seem to be a useful way to classify questions.

Hehe, Mariano, by that reasoning we could as well get rid of the at.algebraic-topology tag... ;P

I'm sorry, I think I am failing to explain my point sufficiently clear. I believe that the critical issue is one of definitions: you are all talking about 'visualization', while I'm talking about 'visual tools', which, at least for me, are two different things (well, visual tools constitute the simplest, most primitive form of visualization, if you wish). Note that, for me, [visual-math] and [math-visualization] would be totally distinct tags, and I agree with you in that the second one is superflous because of its long range (and it is actually comprehended between [intuition], [soft-question], [examples] and other already existing tags).

As Scott very well explained above, "I strongly agree with Yemon that my first example about the octahedral example has nothing to do with visualization, it's purely asking how to render a diagram in LaTeX". But that's precisely my point! It has NOTHING to do with visualization in the broad sense, it just has to do with a question about a visual tool - namely, how to make a good presentation of an octahedral diagram.

I'd like to explain my reasons for tagging the questions you listed above (and see if I slipped on many of them), but here in Spain it is 5.50 in the morning... and I am really tired (have yet to get some sleep!). Is there any way to fix the problem I caused, bring this interesting discussion to a stall for a while, and resume it later?

Anyways, thank you for wanting to arrive to an agreement about the scope of the tag! It is very reasonable and kind of you.

(Edit: It is 6.10 and I really need to go to bed now. If there is an expeditive way to undo what I did, and you feel it necessary to use it, go ahead. We always can arrive to an agreement and retag the selected ones later on)

My opinion is that whenever someone introduces a new tag they should do so on a limited number of questions (maybe not more than ten) and then see how the community receives this new tag. If the tag becomes popular then you win, otherwise it shows that there is no general demand and that introducing this tag might not be as helpful to the community. That is, I don't think it is proper etiquette for a unique user to use a tag on as many threads as Jose did today.

Seconded.

I would like to restart this thread, to re-ask the original question: is there a way to do massive retagging without bumping questions to the front page? The "stochastic-processes" tag seems very useful to me and could accurately and usefully be added to lots of questions.

If the best way for this to occur is for me to compile a list of such questions and then hand the list over to a moderator, that's fine with me. I just don't know if this is the best way to go about it. Suggestions?

I would also like to know if retagging can be done without reactivating questions. I've now accidentally reactivated half a dozen questions from different times due to minor cleanup of little tags (as in http://tea.mathoverflow.net/discussion/975/removingretagging-small-tags/ ), /and/ because that counts as an edit, to my embarrassment they display as if I've asked all of them.

There is no shame in pulling up a couple of old questions for some oxygen. It's even a good thing. It should only be cause for embarrassment if you're really flooding the home page or if you're bumping terrible questions.