# Missing “tt” Ligature

I'm getting bitten by the unfortunate fact that most TeX fonts have an "ff" ligature, but no "tt" ligature. In my field of research, we often denote logical truth by \textbf{tt} and falsehood by \textbf{ff}. Due to the missing-ligature problem, these look quite different.

Now I could surely disable the "ff" ligature in this case, but I find that \textbf{ff} looks considerably better than \textbf{f{}f}. I can also create a poor-man's "tt" ligature by \textbf{t\hspace{-1pt}t}, but the good value of -1pt varies depending on the font size.

How can I consistently enable a ligature in \textbf{tt} so that this automatically looks good in all font sizes?

(I'm currently using lmodern, but'd prefer a universal answer.)

• I'm certainly not a font expert, but I don't believe lmodern has a tt ligature. Unless you want to design one, I think your best bet is using a font that has the ligature. tex.stackexchange.com/questions/153071/… has an example where the questioner wants to not have a tt ligature. You could try that font. – TH. Apr 6 '18 at 6:17
• \textbf{t$\!$t} seems to work for lmodern, but he result is poor for palatino. – corporal Apr 6 '18 at 6:26
• One of the reasons a 'tt' ligature gives trouble in PDF is the absence of a defined unicode codepoint for that ligature. Perhaps that's also why that ligature is rare in fonts – remco Apr 6 '18 at 6:40
• The Linux Libertine font offers a tt ligature. – Mico Apr 6 '18 at 7:08
• Several fonts don't have an “ff” ligature, notably Palatino or Utopia. – egreg Apr 6 '18 at 7:20