Suggestions for the design of a font for math articles/books

Question

Recently I've resumed work on a font I'm currently developing, meant to be released as a completely free, open-source, OFL-licensed font designed specifically for use in papers, theses, books, lecture notes, and any kind of mathematics document more generally. It will consist of a family of fonts for text together with a family of fonts of matching style for math mode.

Since there are many typographical choices and specificities connected to mathematical practice, I wanted to ask for suggestions/wanted features from other mathematicians, in particular from those working in areas different from mine, which might have slightly different typographical needs which I'm not aware of.

As a concrete example of this, having support for letters from other alphabets used as math symbols is important in some areas, such as Ш for the Tate–Shafarevich group in arithmetic geometry, or よ for the Yoneda embedding in category theory.

A different kind of suggestion would be LaTeX specific optimisations or features for fonts which would be nice to have in practice, including e.g. a bigger set of delimiters, or built-in optimisation of microtype through a variable width axis (as e.g. discussed here), a feature relating to the text part of the font.

That said, in a vacuum a question like "Suggestions for features a math font should have" would arguably at best be a soft question, and at worst off-topic for MathOverflow. Nevertheless, given the free, open-source, nature of the font and the fact that ultimately it will be available to the broad mathematical community, I believe it would be reasonable to make an exception in this case, asking for input from the broad mathematical community as part of developing the font with the community in mind, and I believe MathOverflow would be a nice place for receiving this kind of input.

So―would it be okay to ask such a question in the main site? There I would define the exact gap the font is meant to fill, as well as give examples of the kind of input I'm looking for as an attempt to focus the question and define it a bit more clearly (although any input is going to be more than welcome)

Answer 1

Here's an alternative way of gathering feedback.

1. Host your project on a standard project repository (like GitHub or something similar).
2. Gather feedback as feature requests on your project.
3. Spread word about your project on social media. (I for one will be willing to come out of Twitter dormancy to share it, since like LSpice I find the idea quite neat.)

Answer 2

Here's a draft for the question on the main site, following Willie's idea.

---

Introduction. I'm currently working on a font family built for use in body type, named "Darwin" (after one of my dogs!), in particular in mathematics articles, books, etc. It is meant to fill the following requirements, of which no currently available fonts for LaTeX fill:

1. It must be completely free and open-source.
2. It must have exceptional symbol coverage among many different languages.
3. It must come with a number of optical sizes, which are additional font families with size-specific optimizations―think an extra font for footnotes, a font for usual paragraph text, and an extra font for book covers.
4. It must come with a matching math font family to uniformise the style across the document. This includes all the usual math symbols as well as font families for \mathbb, \mathsf, etc.

I believe Linus Romer's Elemaints typeface will fill the above gap well too once it's ready. Darwin will then work as an additional option with a significantly different style, similarly to Computer Modern vs. Palatino or Libertine.

Currently the regular style of the font looks like this (please ignore the bad spacing): PDF samples in English, Russian, and Greek are available here. These were compiled from sources of papers directly downloaded from the arXiv―I bear no relation to their authors.

---

Question. Throughout my own research as well as discussions with friends and colleagues, I've often found situations in math which require special symbols or features from fonts/LaTeX packages, as well as distinct preferences when it comes to certain choices of fonts. For example, these include:

1. The use of symbols that are specific to certain areas and not covered usually, like the hiragana よ for the Yoneda embedding in category theory, the Cyrillic letter Ш for the Tate--Shafarevich group in arithmetic geometry, the Cyrillic letter Л for the Lobachevsky function in hyperbolic geometry, the Cyrillic letter Э for evolutionary vector fields on a jet bundle in some articles (e.g. page 14 of arXiv:0410185 on the geometry of PDEs (as pointed out by Igor Khavkine), etc.
2. Better glyph support for \mathcal, \mathbb, \mathfrak, etc., ranging from \mathbb for the lowercase alphabet, to \mathbb for Greek, to more exotic things like \mathcal or \mathfrak for Greek. Appropriate support for these should have the style of the new symbols match the rest of the document, something which current workarounds like \usepackage[bbgreekl]{mathbbol} fail to fulfill.
3. A preference of "empty fill" over double-strucked blackboard bold or vice versa (i.e. ams vs txof \mathbb).
4. A bigger set of delimiters, as discussed here, for situations where one would e.g. need parentheses bigger than \big(\big) but smaller than \Big(\Big).
5. Built-in optimisation of microtype through a variable width axis, allowing for an even better spacing optimisation than microtype already wonderfully does.

I plan to address all these points in the development of Darwin, adding all Cyrillic glyphs for mathematics, designing matching families for \mathbb Greek and alike, having an option available to choose between one of the two styles of blackboard bold above, as well as implementing the LaTeX specific features outlined in Items 4 and 5 above.

However, I'm sure the above list is anything but exhaustive, and there ought to be countless more such features which would benefit the community. So, in the spirit of the items above, I'd like to ask: are there any font features you want to have as part of your work, but weren't available or required workarounds at the time you thought of them?

Here features should be understood as including things in the spirit of the above examples, but not limited to them.

I also want to point out that suggestions without technical details (like implementations in LaTeX) are very welcome as well, e.g. "this symbol sketched below would work great for doing [x] in area [y], but I'm not aware of an implementation of it, or find the current ones flawed because of [reason]"