bussproofs: How to make lines in the "prooftree" environment look thicker?

Question

This is the code:

\documentclass{article}
\usepackage{bussproofs}
\usepackage[fontsize=32pt]{fontsize}
\begin{document}
\begin{prooftree}
\AxiomC{$a < b$}
\AxiomC{$b < c$}
\BinaryInfC{$ a < c $}
\end{prooftree}
\end{document}

I'm getting:

As you see, that the horizontal bar is thiner than the lines of the < and > symbols. The problem is that the weight of the bar is fixed, while the weight of the lines in the symbols depends on the font size. How can I change the thickness of the bar?

Answer 1

• Not an answer, a comment with pictures :).
• The CTAN entry contains an example document.
• When you zoom into the example document, then it looks different from your screenshot.
• In my PDF viewer, the line width varies a lot depending on the zoom level.
• Maybe this "discovery" helps.

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I also tried \solidLine but with no visible effect on my end.

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Update

Chapter 5.3 Inference-line styles sound promising, or not?

Conclusion

In conclusion, the following part of the manual was crucial:

"The default setting of \ruleScoreFiller is {\hrule}, and in LATEX an unqualified \hrulecommand produces a horizontal line of thickness 0.4 pt. To change the rule’s thickness, use the command \def\ruleScoreFiller{\hrule height new-thickness}."