RE: [EXTERNAL] Re: Minutes: MathML Core Meeting, July 13, 2020

I think I might know what’s confusing here since I was confused a bit about it when I first studied MathML back in the 1990s.

<mrow> is a generic container that in most XML formats would be a set of individually named containers. To find out the nature of an <mrow> container, you parse it. An example is the integral

<mrow>
<msubsup>
<mo>∫</mo>
<mn>0</mn>
<mi>a</mi>
              </msubsup>
<mrow>
<mi>x</mi>
<mi>ⅆ</mi>
<mi>x</mi>
</mrow>
</mrow>

And the trigonometric function

<mrow>
              <mi>sin</mi>
              <mo>&x2061;</mo>
              <mi>x</mo>
</mrow>

Ironically <mfenced> has been deprecated for web use, so <mrow> infix should be used for that too.

In OMML, which probably overdoes explicit elements, all three of these <mrow> containers have explicit names, namely, <nary>, <func>, and <d>, respectively. In addition, all OMML object arguments have explicit names, such as <num>, <den>, <sub> and <sup>.

Some containers like <math> and <msqrt> are “mrow-like” in that they can have an arbitrary number of children, but you know the meanings of these containers up front without parsing.

<mrow> and mrow-like containers have some common properties from a display point of view, such as stretching vertically stretchy symbols. Also an <mrow> acts as a single argument for elements like <mfrac>.that have positional arguments,

Presentation MathML is unique AFAIK in these respects. Other XMLs that I’ve worked with over the years have explicit elements that are all prefix in nature, rather than a mixture of infix and prefix. I’m used to infix since UnicodeMath and math itself have much infix notation. But I can sympathize with folks who might be confused at least at first  by MathML’s <mrow> and positional arguments.

Murray

From: Neil Soiffer<mailto:soiffer@alum.mit.edu>
Sent: Friday, July 17, 2020 3:05 PM
To: Frédéric Wang<mailto:fwang@igalia.com>
Cc: public-mathml4@w3.org<mailto:public-mathml4@w3.org>
Subject: [EXTERNAL] Re: Minutes: MathML Core Meeting, July 13, 2020

I don't feel an explanation is needed, but Brian said he and others who don't live and breathe MathML were confused by "mrow-like".  With the change to "grouping", I don't know if an explanation is needed; he would be better positioned to answer this. The other ones (scripted, radical) don't have explanations. Seems to me if you give an explanation for one of the three, you should do it for all three.

    Neil


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On Thu, Jul 16, 2020 at 9:01 AM Frédéric Wang <fwang@igalia.com<mailto:fwang@igalia.com>> wrote:
On 13/07/2020 23:32, Neil Soiffer wrote:

like: #221<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fmathml-refresh%2Fmathml%2Fissues%2F221&data=02%7C01%7Cmurrays%40exchange.microsoft.com%7C7455e0a6aca84bcbe37f08d82a9d76d9%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637306203078375392&sdata=Bmm7yJtInkED%2F8veVwMJeZG7AIjl%2FT6xfQAMrUfhG3I%3D&reserved=0>

BK: said he and others were confused by the definition of “mrow-like” in the spec. What properties of mrows are shared between them?

NS and DC: it is just a list of elements-- it says nothing about the properties.

BK: people read things into the name and ask how they are “like” each other.

BK: FW suggested in a comment on the issue it could be renamed as “grouping elements” and potentially similar names for “scripted elements”. I think that is less confusing.

NS: There is no definition for “script-like”, so this is really just about changing the one name unless FW is planning on a bigger rewrite which doesn’t seem necessary.

https://mathml-refresh.github.io/mathml-core/#mathml-elements-and-attributes<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fmathml-refresh.github.io%2Fmathml-core%2F%23mathml-elements-and-attributes&data=02%7C01%7Cmurrays%40exchange.microsoft.com%7C7455e0a6aca84bcbe37f08d82a9d76d9%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637306203078375392&sdata=HnXbLq7doWwe5UNpDtPGyjpj8mKyZqQJx3BU8qAqbOg%3D&reserved=0>

has 3 definitions: "mrow-like elements", "scripted elements" and "radical elements".

I think Brian suggested 2 things: rename "mrow-like" and add brief explanation ( https://github.com/mathml-refresh/mathml/issues/221#issuecomment-641743332<https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fmathml-refresh%2Fmathml%2Fissues%2F221%23issuecomment-641743332&data=02%7C01%7Cmurrays%40exchange.microsoft.com%7C7455e0a6aca84bcbe37f08d82a9d76d9%7C72f988bf86f141af91ab2d7cd011db47%7C0%7C0%7C637306203078385382&sdata=qGmatInOcPHH0hUYKn0V9G%2FbHR7sPHDkWpD0mUPOn5I%3D&reserved=0> ). These are pure renaming and explanatory comment, the definitions itself remain unchanged.

I understand there was consensus on the renaming. Do I also need to add a brief explanation in this section too?

--

Frédéric Wang