From 37c2a294e3f374bfd53b85aa7535b416a5d42732 Mon Sep 17 00:00:00 2001 From: Calvin Lee Date: Tue, 12 Sep 2023 18:22:51 +0000 Subject: [PATCH] add fep: Formatting Mathematics --- fep/dc88/fep-dc88.md | 161 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 161 insertions(+) create mode 100644 fep/dc88/fep-dc88.md diff --git a/fep/dc88/fep-dc88.md b/fep/dc88/fep-dc88.md new file mode 100644 index 0000000..0bc03b3 --- /dev/null +++ b/fep/dc88/fep-dc88.md @@ -0,0 +1,161 @@ +--- +slug: "dc88" +authors: Calvin Lee +status: DRAFT +dateReceived: 1970-01-01 +--- +# FEP-dc88: Formatting Mathematics + + +## Summary + +This FEP recommends a method for formatting mathematics in ActivityPub +post content in [MathML Core]. Furthermore, this FEP describes how to +sanitize and convert such mathematics to plain text, if an +implementation does not wish to support mathematical formatting. + + +## Requirements + +The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, +“SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this +specification are to be interpreted as described in [RFC-2119]. “The +implementation” is to be interpreted as an ActivityPub conformant +Client, ActivityPub conformant Server or ActivityPub conformant +Federated Server as described in [ActivityPub] which wishes to produce +or consume mathematically formatted content. + + +## History + +Written mathematics depends very heavily on a system of notation which +has been continuously evolving over thousands of years. Despite its +ubiquity, mathematical notation is anything but constant. Mathematicians +rely heavily on complicated typesetting systems such as [LaTeX] to +layout text in their desired fashion. + +Several fediverse instances, such as [Mathstodon] have emerged to host +discussion related to mathematics. This is to no small part due to the +difficulty of conveying and formatting mathematical text, and many +provide their own typesetting implementation based on [LaTeX]. However, +rendering TeX-like formats is expensive and fraught with issues due to +security and implementation-specific quirks. This has resulted in +multiple instances with incompatible TeX-like implementations. + +In recent years, [MathML Core] has become standardized by all major web +browsers, and offers an alternative method to communicate mathematics +between differing fediverse implementations that is compatible with the +ActivityPub standard. + + +## Formatting Mathematics + +The implementation MAY produce mathematical formatting in the +`summary` or `content` properties of [ActivityStreams] objects, as +defined in [Activity Vocabulary] if the `mediaType` is `text/HTML` (the +default). This formatting MUST be placed within one or more top-level +`` elements, hereon referred to as 'a math element'. + +A math element MUST contain one `` child element, and no +other children. The `` element MUST contain a [MathML Core] +expression as its first child, and at least one `` element. +The `encoding` property of this `` element SHOULD be +`"application/x-tex"`, but MAY be `"text/plain"`, and MUST contain +a plain-text description of the mathematics—preferably in the authored +format. The implementation MAY include additional `` or +`` elements with other semantic information. + +All elements contained within a math element MUST be **MathML Core +Elements** as defined in [MathML Core], excluding those contained within +`` elements. + + +## Sanitizing Mathematically Formatted Text + +The implementation SHOULD sanitize incoming mathematical formatting +before displaying it to a user. There are two methods by which an +implementation may sanitize incoming mathematical formatting. + + +### Sanitizing a math element + +The implementation MAY sanitize a math element before displaying it to +a user. The implementation SHOULD remove all non **MathML Core +Elements** as defined in [MathML Core]. The implementation MAY remove +any attribute which does not contain semantic information (see [Semantic +Attributes]). The implementation SHALL NOT remove any [Semantic +Attributes] or **MathML core Elements** and instead should replace +a math element with text. + + +### Replacing a math element with text + +The implementation MAY remove a math element completely, and replace it +with text within the `` element with encoding +`"application/x-tex"` as described in [Formatting Mathematics] and +SHOULD fall back to a `"text/plain"` annotation. If a math element is +not formatted as described in [Formatting Mathematics], then the +implementation MUST remove it completely. + +The implementation MAY surround the text from the `` element +with a pair of delimiters. For example, if a math element has the +attribute `display="block"`, it may choose the delimiters `$$` and `$$`, +and if `displaystyle="inline"` it may choose `$` and `$` to match the +TeX typesetting system. + +## Examples +```json +{"@context": ["https://www.w3.org/ns/activitystreams", {"@language": "en"}], + "type": "Note", + "id": "http://postparty.example/p/2415", + "content": "I have a truly marvelous proof that + + + + xn + + + yn + ≠ + zn + + x^n+y^n\\ne z^n + + + which this note is too small to contain!", + "source": { + "content": "I have a truly marvelous proof that \\(x^n+y^n\\ne z^n\\) which this note is too small to contain!", + "mediaType": "text/markdown+math"}} +``` + +This object's source content represents a valid sanitization of its +`content` field. + + +## Semantic Attributes + +| Element | Attributes | Values | +| ------- | ------------ | ---------------- | +| all | `mathvariant` | `normal` | +| all | `displaystyle`, `scriptlevel` | all | +| `` | `display` | all | +| `` | `linethickness` | `0`, `1` | +| ``| `width`, `height`, `depth` | all | +| `` | `form` `stretchy`, `symmetric`, `largeop`, `movablelimits`, `lspace`, `rspace`, `minsize`, | all | + + +## References + +- [ActivityPub] Christine Lemmer Webber, Jessica Tallon, [ActivityPub](https://www.w3.org/TR/activitypub/), 2018 +- [ActivityStreams] James M Snell, Evan Prodromou, [ActivityStreams 2.0](https://www.w3.org/TR/activitystreams-core), 2017 +- [Activity Vocabulary] James M Snell, Evan Prodromou, [Activity Vocabulary](https://www.w3.org/TR/activitystreams-vocabulary/), 2017 +- [LaTeX] LaTeX authors, [The LaTeX Project](www.latex-project.org) +- [MathML Core] David Carlisle, Frédéric Wang, [MathML Core W3C Candidate Reccomendation Snapshot](https://w3c.github.io/mathml-core/), 2023 +- [Mathstodon] Mathstodon Admins, [About Mathstodon](https://mathstodon.xyz/about), retrieved 2023 +- [RFC-2119] S. Bradner, [Key words for use in RFCs to Indicate Requirement Levels](https://datatracker.ietf.org/doc/html/rfc2119), 1997 + + +## Copyright + +CC0 1.0 Universal (CC0 1.0) Public Domain Dedication + +To the extent possible under law, the authors of this Fediverse Enhancement Proposal have waived all copyright and related or neighboring rights to this work.