RE: [EXTERNAL] Semantic Markup: mrow's are needed

I guess I’m used to parsing UnicodeMath and LaTeX and am not confused by the examples below at all. It’s easy to add the extra <mrow>’s if need be. Being mathematically inclined, I like succinct notations. Marking things up with lots of syntactic sugar that can be easily inferred seems to be a step backward and introduces complexity that can be error prone. If the usual operator precedence rules are to be overruled, then that’s when you need to add the extra <mrow>’s. And I really like implicit <mrow>’s since they are unambiguous and facilitate reading MathML.

In this vein, we really need to define a set of defaults that apply to K-12 math. Explicitly saying that an mfrac is an ordinary fraction seems crazy and error prone. Furthermore we have to handle MathML that doesn’t have any such extra markup and we can already do so reliably. Only non-default expressions need special markup.

One other idea: I think the main goal is to be able to speak math expressions correctly. Being able to compute non-default math expressions is a more advanced goal that’s worth pursuing but is clearly harder and shouldn’t delay our coming up with a set of speech hints.

Thanks,
Murray

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From: Neil Soiffer<mailto:soiffer@alum.mit.edu>
Sent: Friday, June 26, 2020 7:40 AM
To: public-mathml4@w3.org<mailto:public-mathml4@w3.org>
Subject: [EXTERNAL] Semantic Markup: mrow's are needed

We have talked a little about needing proper mrow structure in order to mark up prefix/posfix/infix operators. For example, the following can not be semantically marked up:
<mrow>
  <mi>m</mi>
  <mo>!</mo>
  <mi>n</mi>
  <mo>!</mo>
</mrow>

It needs an extra layer of mrows around the postfix factorials in the mrow.
<mrow>
  <mrow>
    <mi>m</mi>
    <mo>!</mo>
  </mrow>
  <mrow>
    <mi>n</mi>
    <mo>!</mo>
  </mrow>
</mrow>

Here's a case we haven't talked about: implicit mrows.
<msqrt>
  <mi>n</mi>
  <mo>!</mo>
</msqrt>

There is no place to markup the factorial here either. Implicit mrows don't work for semantic markup.

Given what MathML generators typically produce, I think this pretty much forces the need for a canonicalization tool for anyone wanting to hand-remediate MathML. For a tool that wants to infer the semantics, it seems necessary also.

More directly actionable though is what we should say in a MathML 4 specification. Specifically,

  *   Should we discourage or maybe even deprecate implicit mrows?

  *   Should we have stronger language encouraging "proper" mrow structure?