おおー、xyJax 使える

次の記事参照、ありがたや

<script type="text/javascript"
        src="https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js?config=TeX-AMS_HTML">
</script>
<script type="text/javascript">// <![CDATA[
        MathJax.Ajax.config.path["Contrib"] = "//cdn.mathjax.org/mathjax/contrib";
        MathJax.Hub.Config({
        CommonHTML: { linebreaks: { automatic: true } },
        "HTML-CSS": { linebreaks: { automatic: true } },
        showProcessingMessages: false,
        tex2jax: {   displayMath: [['$$','$$']] },
        TeX: { equationNumbers: { autoNumber: "AMS" }, TagSide: "left", TagIndent: "0em",
        extensions: ["AMSmath.js","AMSsymbols.js","[Contrib]/xyjax/xypic.js"] }});
// ]]></script>

↑これに、inlineMath: [['$`', '`$']], を追加して、余分なところを削って、

<script
        src="https://cdn.jsdelivr.net/npm/mathjax@2/MathJax.js?config=TeX-AMS_HTML">
</script>
<script>
        MathJax.Ajax.config.path["Contrib"] = "//cdn.mathjax.org/mathjax/contrib";
        MathJax.Hub.Config({
        CommonHTML: { linebreaks: { automatic: true } },
        "HTML-CSS": { linebreaks: { automatic: true } },
        showProcessingMessages: false,
        tex2jax: {  inlineMath: [['$`', '`$']], displayMath: [['$$','$$']] },
        TeX: { equationNumbers: { autoNumber: "AMS" }, TagSide: "left", TagIndent: "0em",
        extensions: ["AMSmath.js","AMSsymbols.js","[Contrib]/xyjax/xypic.js"] }});
</script>

scriptタグに async 付けたら xyJax がダメになった。

XyPic のマニュアルは: