I'm writting my thesis with the classicalthesis package. I have a problem with long chapter titles being too long for headings. For that reason I use the short title option (in Lyx). By definition the short titles are used for the Table of Content but I want them to be long in the TOC. I read


and I used the titlesec package with the "toctitles" option in the (LaTeX) preamble in LyX, but I get an error message form Lyx:

LaTeX Error: Option clash for package titlesec. Use of \@chapter doesn't match its definition.

Sorry I dont know how to attach example files in my question, I attach two pictures: Long and short title Chapter PDF generate Please see the content list

  • 1
    I do not use LyX, but if you are able to edit the TeX source, you should read tex.stackexchange.com/q/6862 and tex.stackexchange.com/q/26234
    – LaRiFaRi
    Dec 9, 2014 at 11:35
  • How to do this depends on the document class in use. There recommended (by the package author) class is of the KOMA bundle. You can define a title for the document, one for the running header and one for the toc. titlesec should not be used with KOMA. To sum it up: We need a compilable example to play with.
    – Johannes_B
    Dec 10, 2014 at 9:51

1 Answer 1


I solved the problem in the following way:

I inserted the following Tex code in Lyx:

\chaptermark{SHORT TITLE} 
\chaptermark{SHORT TITLE}
  • It looks like you've got two separate accounts, which means you cannot edit your original post or leave comments. The StackExchange staff can merge them together for you.
    – Johannes_B
    Dec 11, 2014 at 14:29

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