Awkward speech and navigation from MathML generated by tex4ebook/make4ht (TeX4ht)

[brichwin]

Description

Institutions trying to meet the new Title II ADA regs and wishing to generate HTML or EPUB3 files from .tex sources are developing processes built upon make4ht and tex4ebook. These tools appear to use TeX4ht to generate MathML for the math expressions. While the math appears to render correctly visually it often yields awkward speech and navigation patterns from MathCAT.

For example, the MathML generated by TeX4ht for the LaTeX \[ \lim_{x\to 2}\frac{x^2-4}{x-2} \] yields this speech from MathCAT ClearSpeak Verbose:

quantity lim of with x right arrow 2 below of; the fraction with numerator; x squared minus 4; and denominator x minus 2; end fraction

Expand to see MathML from TeX4ht

<?xml version="1.0" encoding="UTF-8"?>
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <mrow>
    <munder class="msub">
      <mrow>
        <mi class="qopname">lim</mi>
        <mo>
          ⁡
          <!-- FUNCTION APPLICATION -->
        </mo>
      </mrow>
      <mrow>
        <mi>x</mi>
        <mo class="MathClass-rel" stretchy="false">→</mo>
        <mn>2</mn>
      </mrow>
    </munder>
    <mfrac>
      <mrow>
        <msup>
          <mrow>
            <mi>x</mi>
          </mrow>
          <mrow>
            <mn>2</mn>
          </mrow>
        </msup>
        <mo class="MathClass-bin" stretchy="false">−</mo>
        <mn>4</mn>
      </mrow>
      <mrow>
        <mi>x</mi>
        <mo class="MathClass-bin" stretchy="false">−</mo>
        <mn>2</mn>
      </mrow>
    </mfrac>
  </mrow>
</math>

Compare that to the speech text generated by MathCAT when MathJax 4.1.1 produces the MathML:

the limit as x approaches 2, of; the fraction with numerator; x squared minus 4; and denominator x minus 2; end fraction

Expand to see MathML from MathJax 4.1.1

<?xml version="1.0" encoding="UTF-8"?>
<math xmlns="http://www.w3.org/1998/Math/MathML" display="block">
  <munder>
    <mo movablelimits="true">lim</mo>
    <mrow>
      <mi>x</mi>
      <mo accent="false" stretchy="false">→</mo>
      <mn>2</mn>
    </mrow>
  </munder>
  <mo>⁡</mo>
  <mfrac>
    <mrow>
      <msup>
        <mi>x</mi>
        <mn>2</mn>
      </msup>
      <mo>−</mo>
      <mn>4</mn>
    </mrow>
    <mrow>
      <mi>x</mi>
      <mo>−</mo>
      <mn>2</mn>
    </mrow>
  </mfrac>
</math>

Expected

It is desirable to hear more naturally sounding speech "The limit as x approaches 2, of..."

[brichwin]

I posted this to MathCAT rather than TeX4ht since I'm guessing that the MathML from TeX4ht is technically valid, if awkward/weird. The key structural differences between the two MathML variants that likely drive the speech difference are:

• TeX4ht wraps lim in <mi> inside an <mrow> alongside a function application operator ⁡, while MathJax uses <mo movablelimits="true">lim</mo>
• TeX4ht places the function application ⁡ inside the <munder> alongside lim, while MathJax places it outside and after the <munder>
• The non-standard class attributes on TeX4ht's elements (class="msub", class="qopname", class="MathClass-rel") are presentational artifacts from TeX4ht. I'm guessing they are ignored by MathCAT

Question: Should this and similar issues be reported to TeX4ht or collected and reported to MathCAT?

[brichwin]

For the curious, lualatex when using the new document metadata settings per the LaTeX3 Tagged PDF project produces MathML from \[ \lim _{x\to 2}\frac {x^2-4}{x-2} \] that yields this speech output from MathCAT:

the limit as x approaches 2, of; the fraction with numerator; x squared minus 4; and denominator x minus 2; end fraction

The MathML it produced was:

<?xml version="1.0" encoding="UTF-8"?>
<math xmlns="http://www.w3.org/1998/Math/MathML">
  <mstyle displaystyle="true" scriptlevel="0">
    <munder>
      <mi mathvariant="normal">lim</mi>
      <mrow>
        <mi>&#x1d465;</mi>
        <mo lspace="0" rspace="0" stretchy="false">→</mo>
        <mn>2</mn>
      </mrow>
    </munder>
    <mspace width="0.167em" />
    <mfrac>
      <mrow>
        <msup>
          <mi>&#x1d465;</mi>
          <mn>2</mn>
        </msup>
        <mo lspace="0.222em" rspace="0.222em">−</mo>
        <mn>4</mn>
      </mrow>
      <mrow>
        <mi>&#x1d465;</mi>
        <mo lspace="0.222em" rspace="0.222em">−</mo>
        <mn>2</mn>
      </mrow>
    </mfrac>
  </mstyle>
</math>