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Subject: Re: [dita] Proposed Enhancement to The Equation Domain


As a follow up, I asked Dr. Leevers if there is ever a requirement to
number inline equations and his answer was no, that there are a number of
good reasons to never number inline equations (not least is that the
number will be hard to find visually and may be confused with the equation
itself).

That means that when an equation is numbered block presentation is
implicit, which means that the presence of the proposed <equation-number>
element is sufficient to trigger block presentation even when there is an
explicit @outputclass value of "inline" (being a case that should probably
be reported as a warning by any processor). It also means that an
@outputclass value of "inline-numbered" is probably inappropriate.

Cheers,

Eliot
-- 
Eliot Kimber
Senior Solutions Architect
"Bringing Strategy, Content, and Technology Together"
Main: 512.554.9368
www.reallysi.com
www.rsuitecms.com




On 2/5/14, 9:56 AM, "Eliot Kimber" <ekimber@rsicms.com> wrote:

>I've been communicating with Dr Patrick Leevers, a professor of
>engineering at Imperial College London, about the new MathML and equation
>domains. Dr. Leevers is working on using DITA as the source for STEM
>course materials, so of course mathematics is extremely important.
>
>The feedback I got from Dr. Leevers is that in mathematical writing the
>decision to display an equation that is within prose as block or inline
>and, for block equations, whether or not to number an equation, is a
>per-equation-instance decision made by the author. He pointed me to these
>dicsussions:
>
>> This discussion about equations and punctuation is good, especially the
>> first and last responses:
>> 
>>http://english.stackexchange.com/questions/31124/should-there-be-a-period
>>-
>> after-an-equation
>> The question of equation numbering enters here:
>> 
>>http://english.stackexchange.com/questions/22535/do-mathematical-equation
>>s
>>-require-punctuation
>> and it takes us to the ultimate authority Knuth (who invented TeX) at
>> http://tex.loria.fr/typographie/mathwriting.pdf
>> who on p4, p7 etc. does punctuation-and-numbers stuff.
>
>
>Dr. Leevers' feedback is also consistent with work I've been doing
>recently for a client that is using DITA to represent scientific journal
>articles, some with many equations--we ran into just these same issues
>around equation flow within paragraphs, capturing and rendering text
>around block equations, and capturing and rendering equation numbers.
>
>The challenge revolves around how to display and whether to number
>equations that are part of a larger sentence.
>
>For example, say I have this sentence:
>
>"The amount of energy in a given unit of mass can be determined by the
>equation E = mc^^2, where E is the energy, m is the mass, and c is the
>speed of light in a vacuum."
>
>
>The equation "E = mc^^2" is part of the sentence grammatically and
>rhetorically. However, the author could choose to render the sentence like
>this:
>
>"The amount of energy in a given unit of mass can be determined by the
>equation 
>
>    E = mc^^2, 
>
>where E is the energy, m is the mass, and c is the speed of light in a
>vacuum."
>
>
>Note the "," after the equation--this reflects that the sentence is still
>a single sentence despite the block display of the equation.
>
>If the author needs to refer to that equation they may decide to add an
>equation number:
>
>"The amount of energy in a given unit of mass can be determined by the
>equation 
>
>    E = mc^^2,    (1)
>
>where E is the energy, m is the mass, and c is the speed of light in a
>vacuum."
>
>This way of using equations has several implications for the current
>design of the equation domain:
>
>1. The block/inline distinction intended by the <equation-block> and
><equation-inline> elements is not useful in this context: in all three of
>the cases above, the only correct element type is <equation-inline> (a
>specialization of <ph>) because in all three cases the content is a
>sentence within a paragraph, e.g.:
>
><p>"The amount of energy in a given unit of mass can be determined by the
>equation
><equation-inline>E = mc^^2</equation-inline>, where E is the energy, m is
>the mass, 
>and c is the speed of light in a vacuum.</p>
>
>
>2. Because numbering can be on a per-instance basis, and because those
>numbers may be completely arbitrary, there needs to be an element
>specifically for specifying the equation number that can be put inside the
>equation container, e.g. <equation-number>.
>
>3. Because numbering is on a per-instance basis, using <equation-figure>
>in place of <equation-inline> simply to trigger numbering is not really
>realistic. For one reason, while <fig> is allowed in <p>, it's not allowed
>in all contexts where <ph> is also allowed (for obvious reasons), so
>equation-figure and equation-inline can't be used interchangeably in the
>general case.
>
>This all leads me to suggest the following refinements to the current
>equation domain design:
>
>1. Define the following values to be used in @outputclass on
><equation-inline>:
>
>- block/inline: Indicates whether the equation should be rendered as block
>or inline, with inline being the default rendering if no value is
>specified.
>
>- block-numbered: Indicates that the equation should be rendered as a
>numbered block equation with the number to be generated if not specified
>explicitly (the normal case).
>
>- inline-numbered: Indicates that the equation should be rendered as a
>numbered inline equation with the number to be generated if not specified
>explicitly (the normal case). This may be a rare case but is included for
>symmetry at least.
>
>I'm using "compound" values here rather than multiple keywords to make
>authoring easier: tools that support using subjectScheme to define
>attribute values don't always support setting multiple keywords (and such
>support requires a more complicated user interface than just a simple
>dropdown list).
>
>2. Define the new element <equation-number>, specialized from <ph> and
>allowed within <equation-block>, <equation-inline>, and <equation-figure>
>. The content of the equation number is the equation number and is used in
>place of any number that might be generated.
>
>Cheers,
>
>Eliot
>
>-- 
>Eliot Kimber
>Senior Solutions Architect
>"Bringing Strategy, Content, and Technology Together"
>Main: 512.554.9368
>www.reallysi.com
>www.rsuitecms.com
>
>



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