JATS: statement support

[rgieseke]

Currently, "statement" is handled with the default encoder in the JATS codec.
This doesn't catch the label/id of a "statement" environment.

E.g. in LaTeX:

The Theorem~\ref{thm:ref} is below.

\begin{theorem}\label{thm:ref}
Let it be.
\end{theorem}

As JATS XML:

<p id="p1">The Theorem&#xA0;<ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="#Thmtheorem1">1</ext-link> is below.</p>
<statement id="Thmtheorem1">
  <title><bold>Theorem 1</bold>.</title>
  <p id="Thmtheorem1.p1">
    <italic>Let it be.</italic>
  </p>
</statement>

As JSON:

{
      "type": "Paragraph",
      "id": "p1",
      "content": [
        "The Theorem ",
        {
          "type": "Link",
          "target": "#Thmtheorem1",
          "content": [
            "1"
          ]
        },
        " is below."
      ]
    },
{
      "type": "Heading",
      "depth": 1,
      "content": [
        {
          "type": "Strong",
          "content": [
            "Theorem 1"
          ]
        },
        "."
      ]
    },
    {
      "type": "Paragraph",
      "id": "Thmtheorem1.p1",
      "content": [
        {
          "type": "Emphasis",
          "content": [
            "Let it be."
          ]
        }
      ]
    }

Should there be a separate "statement" element?

JATS defines it as:

Theorem, Lemma, Proof, Postulate, Hypothesis, Proposition, Corollary, or other formal statement, identified as such with a label and usually made typographically distinct from the surrounding text.

https://jats.nlm.nih.gov/publishing/tag-library/1.2/element/statement.html

In LaTeX this would be a "theorem" and one of the many variants.
https://www.overleaf.com/learn/latex/theorems_and_proofs

Typically theorem titles are rendered inline, so another solution might be to just have a Block element wrapper (with id and some kind of information about the type) around the statement content.

[nokome]

I can certainly see the case for adding a Statement type, perhaps similar to a Figure but without caption ?https://github.com/stencila/schema/blob/master/schema/Figure.schema.yaml

[nokome]

Where possible we try to reuse schema.org terms. I wonder if Claim could be reused here https://schema.org/Claim

[rgieseke]

While their original intention seems to have been more about general fact checking i think this could be a pretty good fit! (One could to a ClaimReview of a mathematical document's theorems and this might enable interesting data mining approaches.)

schemaorg/schemaorg#1969

In JATS:

<label> Label (of an Equation, Figure, Reference, etc.), zero or one
<title> Title, zero or one
<abstract> Abstract, zero or more
<kwd-group> Keyword Group, zero or more
One or more of any of:

    <p> Paragraph
    <statement> Statement, Formal

In schema.org Claim:

• a stencila.Label? Not sure about this one.
• name or headline?
• abstract
• keywords
• text