Incorrect Spacing around \because and \therefore

[jonathan-gruber-jg]

The unicode-math package seems to produce incorrect spacing around \because and \therefore from the amssymb package. To demonstrate this, compare the spacing around \because and \therefore in the output of the below example when unicode-math is included vs. excluded. The font may be different when unicode-math is included vs. excluded, but the thing to focus on is the spacing around \because and \therefore in the output.

\documentclass{article}

\usepackage{amssymb}
% Comment or uncomment the below line to compare the behavior when unicode-math is included vs. excluded.
\usepackage{unicode-math}

\begin{document}
\[
    1 \because 1
\]
\[
    1 \therefore 1
\]
\end{document}

There may be other symbols exhibiting this same behavior, but I have not checked. If you discover other symbols exhibiting this behavior, feel free to note this in a reply to this post.

TeX distribution: TeX Live 2025
TeX version: 3.141592653
XeTeX version: 3.141592653-2.6-0.999997
LuaTeX version: 1.22.0
unicode-math version: 0.8r 2023-08-13

[davidcarlisle]

amssymb has

\DeclareMathSymbol{\because}      {\mathrel}{AMSa}{"2A}

so mathrel spacing

unicode-math has

\UnicodeMathSymbol{"02235}{\because                  }{\mathord}{because}%

so mathord spacing

Hmm unicode-math mostly follows the mathclass assignments from Unicode TR25 but MathClass-15.txt has

2235;R

which agrees with amssymb and classes this as a relation.

#619 has a more general comparison with the UTR25 data.