Re: equations

[Norman Walsh <ndw@nwalsh.com>]

/ Doug du Boulay <ddb@owari.msl.titech.ac.jp> was heard to say:
| Norman Walsh <ndw@nwalsh.com> wrote:
|> DocBook NG still has both the formal and informal versions.
|> 
|> The odd man out in all this is equation which, for backwards
|> compatibility reasons in DocBook *4* still has an *optional* title,
|> even though there's also an informalequation element. I see two
|> possible ways forward:
|> 
|>   1. Keep the formal/informal distinction and make title on equation
|>      required. (This is what I've actually done in DocBook NG.)
|> 
|>   2. Drop the distinction, drop informal{equation,table,example,figure}
|>      and make title on all those elements optional.
|> 
|> Option 1 is probably easier for users and for tools, so I'm inclined
|> to go that way at the moment. The only advantage to option 2, really,
|> is that DocBook becomes four elements smaller. But the semantic
|> disjunction is probably too high a price to pay.
|
| For the record, even though many equations do actually have names,
| in the scientific literature I think you will find exactly zero instances 
| of titles on equations (for that matter there would be no TOC equation 
| lists iether). For this reason IMHO option 1 would actually be a backwards 
| step hindering the adoption of DocBook amongst a broader
| community. 

Hmm. So requiring title on equation is likely to be controversial :-)

| Customarily equation blocks fall into two classes, these being
| numerically labelled and unlabelled equations. The existing equation and 
| informalequation elements provide a useful method for distinguishing
| between those cases and my hope is that they could be retained. 

Ah, so you use

  <equation>
    equation content
  </equation>

(without a title) for equations that should be labeled with a number
and

  <informalequation>
    equation content
  </informalequation>

for ones that shouldn't be numbered?

| Its a shame there isn't a third option:
|
|     3. The equation element be shifted out from the formal list into 
|         a group of its own, because in reality it has a completely 
|         different usage model.

Voila! A third option :-)

| Alternatively, if option 2 was adopted could some other standardised
| means be established to discriminate between labelled and unlabelled 
| equation blocks?

Yes, let's forget the informal/formal distinction for equations. My
ideas were clearly based on a failure to understand how it's actually
used in practice (my bad).

How would you suggest distinguishing between labeled and unlabeled
equations?

                                        Be seeing you,
                                          norm

-- 
Norman Walsh <ndw@nwalsh.com>      | Men do not quit playing because
http://www.oasis-open.org/docbook/ | they grow old; they grow old
Chair, DocBook Technical Committee | because they quit playing.--Oliver
                                   | Wendell Holmes

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