I'm relatively baffled by the behavior of the following MWE. As far as I can tell, there is nothing wrong with the .bib entries. However, trying to compile this document (biblatex v3.3 and biber v2.4) results in the following error:

! Extra }, or forgotten $.
<recently read> }



If you make the relevant changes to use natbib instead, the MWE compiles just fine.

% !TEX encoding = UTF-8 Unicode
% !TEX TS-program = arara
% arara: lualatex: { synctex: no }
% arara: biber
% arara: lualatex: { synctex: yes }

    Author = {Belletti, Adriana and Rizzi, Luigi},
    Doi = {10.1007/BF00133902},
    Journal = {Natural Language \& Linguistic Theory},
    Month = {August},
    Number = {3},
    Pages = {291--352},
    Title = {Psych-Verbs and $\theta$-Theory},
    Volume = {6},
    Year = {1988}}











The resulting .bbl file looks fine, as far as I can tell, which leads me to think it's a problem with biblatex, but I'm really not sure. Here's the resulting .bbl file:

% $ biblatex auxiliary file $
% $ biblatex bbl format version 2.6 $
% Do not modify the above lines!
% This is an auxiliary file used by the 'biblatex' package.
% This file may safely be deleted. It will be recreated by
% biber as required.
     {Missing 'biblatex' package}
     {The bibliography requires the 'biblatex' package.}

      \field{journaltitle}{Natural Language \& Linguistic Theory}
      \field{title}{Psych-Verbs and $\theta$-Theory}
      \field{pages}{291\bibrangedash 352}
      \verb 10.1007/BF00133902

Most interestingly, if you wrap $\theta$ in braces, everything works fine, e.g.:

    Title = {Psych-Verbs and {$\theta$}-Theory},

As far as I know, this is not something that has ever been required with biblatex and Biber. Am I incorrect, or is this a bug?

  • What's it putting in the .bbl? Is it a Biber issue or a Biblatex one? – cfr Apr 22 '16 at 3:14
  • @cfr Just posted some updates that hopefully clarify things, though I'm about to head to bed. Good night! :) – Adam Liter Apr 22 '16 at 3:30
  • The issue has to do with the \MakeSentenceCase macro, it can be reproduced with the standard styles and \DeclareFieldFormat{titlecase}{\MakeSentenceCase{#1}}. – moewe Apr 22 '16 at 5:19
  • It works fine if you protect the math with a brace: Title = {Psych-Verbs and {$\theta$}-Theory}, (this is the recommended method to protect unusual input from \MakeSentenceCase, see the docu). – Ulrike Fischer Apr 22 '16 at 8:10
  • Sorry didn't see that you actually had already found the braces. As the documentation says: \MakeSentenceCase "support the traditional BibTeX convention for bib files that anything wrapped in a pair of curly braces is not modified when changing the case." and shows some example how to use it in case you don't want it to kick in. – Ulrike Fischer Apr 22 '16 at 8:22

The definition of \MakeSentenceCase needs to allow for math mode. A possible fix is



| improve this answer | |
  • 2
    Do you think this is robust enough to go into the next biblatex release? – PLK Apr 22 '16 at 8:17
  • 1
    Thanks Joseph! :) It would be nice if this could make it into a biblatex release at some point, as this seems like a case that biblatex should be able to handle. – Adam Liter Apr 22 '16 at 18:31
  • Was just curious if this ever made it into a biblatex release or if it ever will? I still seem to be having this problem (CC: @PLK). – Adam Liter Nov 29 '17 at 15:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.