How to ensure that bibliography and caption style are fully respected in extension?

[pat-alt]

Description

Hi there,

I'm working on a journal extension for ECML (they use the Springer LNCS Template). The extension is here: open the repo on GH. The rendered template (PDF) looks almost identical to the target (PDF), but I'm struggling to resolve two final things:

1. Caption styling defined in llncs.cls does not seem to be applied.
2. The bibliography formatting is off even though \bibliographystyle{splncs04} is included in the final .tex file.

Regarding (1), I'm assuming Quarto/Pandoc overwrites the styling, but I can see that existing templates seem to avoid this issue somehow: open quarto-cli repo search for 'make caption'. It's just not clear to me how exactly, so I'd be grateful for any pointers.

As for the bibliography formatting, I'm using the following approach:

---
pdf:
   cite-method: natbib
   biblio-style: splncs04
   natbib: true
   natbiboptions: numbers, compress
   link-citations: false
---

This does give me numbered citations in square brackets, but the bibliography itself does not seem to comply fully with the style (using square brackets (i.e. [1] Author ...) instead of dots (i.e. 1. Author ...).

Any pointers would be much appreciated - thanks!

[mcanouil]

Did you check the LaTeX document produced and investigate it? (keep-tex: true).

[pat-alt]

Thanks for the quick reply!

Yes, so I can see in line 6 of the template.tex file that the document class is determined as expected (set in the template partial located at partials/doc-class.tex).

Looking at the commands for the table (open line 186 of the template.tex file) and the figure (open line 228 of the template.tex file), I also cannot spot anything that should interfere with the styling being applied.

As for the bibliography, the style is set in the preamble (in line 109 of the template.tex) and then the bibliography is generated in line 290 of the template.tex file. Again, I can see what might be causing the discrepancy but I'm probably missing something.

[mcanouil]

Side note about accessibility: could you avoid using "here" and "caption" as text for links? See Writing meaningful link text

[pat-alt]

Thanks for flagging, I've adjusted the comment

[cderv]

@pat-alt did you try using your llncs.cls and splncs04.bst together to format a .tex with reference, and see if you get expected style ?

I don't see which part of Quarto could interfere here. Looking a the .cls file and the .bst file I see hint that [ ] maybe the expected syntax

FUNCTION {output.bibitem}
{ newline$
  "\bibitem{" write$
  cite$ write$
  "}" write$
  newline$
  ""
  before.all 'output.state :=
}

Here it seems \bibitem is what defines the numbering used
The .cls file has some behavior and conditional that modify how numbering is done I believe
https://github.com/pat-alt/quarto-ecml/blob/0a04aa4e76e4e40e5476023fcd003fe4c4a0a6ea/_extensions/quarto-ecml/llncs.cls#L680-L768

It is supposed to be conditional to a class option set
https://github.com/pat-alt/quarto-ecml/blob/0a04aa4e76e4e40e5476023fcd003fe4c4a0a6ea/_extensions/quarto-ecml/llncs.cls#L27

\DeclareOption{citeauthoryear}{\let\citeauthoryear=Y}

This means that when option is set, the command \citeauthoryear will be defined, but in fact natbib defines this command I believe - so it seems to me there is a conflict.

Does the template really support natbib ?

I hope this helps you and give you some hints to put you on the right tract. To solve this, I really advice that you understand how this works at the LaTeX level from the tex file generated by Quarto, or starting from another tex file.

Once you know what is compatible or not, you can adapt the option of Quarto to get the right insertion in pandoc template.

[pat-alt]

Thanks a lot for your suggestions @cderv. Indeed, I think natbib was the wrong route here. I've instead tried two approaches:

1. Use a Lua filter to ensure that @mycitation2025 gets converted to \cite{mycitation2025} and then just include \bibliography{bibliography}.
2. Use the springer-lecture-notes-in-computer-science.csl file: open the publicly available file.

Regarding the first approach, the following filter works as expected:

return {
    Cite = function(el)
      if quarto.doc.is_format("latex") then
        -- Check if any citation ID does NOT contain a dash
        -- (indicating it's likely a bibliographic citation)
        local isCitation = false
        for _, cite in ipairs(el.citations) do
          if not cite.id:match("-") then
            isCitation = true
            break
          end
        end
        
        if isCitation then
          local cites = el.citations:map(function(cite)
            return cite.id
          end)
          local citesStr = "\\cite{" .. table.concat(cites, ",") .. "}"
          return pandoc.RawInline("latex", citesStr)
        end
      end
      return el
    end
}

but \bibliography{bibliography} seems to have no effect (no references show up).

The second approach gets me pretty close to the desired style, but it does not use the splncs04.bst at all.

@pat-alt did you try using your llncs.cls and splncs04.bst together to format a .tex with reference, and see if you get expected style ?

Yes, simply using the LaTeX template (i.e. no involvement of Quarto/Pandoc) works as expected.

I'm going to have to work on my actual submission now but hope to turn back to this, so hope it's okay to keep the discussion open.

In the meantime, does either of the two approaches above make sense? Or am I going down rabbit holes?

Many thanks!

[cderv]

The second approach gets me pretty close to the desired style, but it does not use the splncs04.bst at all.

This is expected. This second approach uses CSL directly though Pandoc's citeproc.

but \bibliography{bibliography} seems to have no effect (no references show up).

Is it included into your .tex output ? Did you opt out Pandoc's citeproc in this case ?

I am wondering about the right part of TeX template being activated.

Yes, simply using the LaTeX template (i.e. no involvement of Quarto/Pandoc) works as expected.

Does this template uses natbib ? What does it use for citation ? I am curious what their template and journal does recommand for processing citation in LaTeX.

You could try using biblatex with Pandoc (and so quarto) instead of natbib maybe.

In the meantime, does either of the two approaches above make sense? Or am I going down rabbit holes?

They make sense

• Second one leverage Pandoc's feature for citation processing, which is perfectly valid. But it won't use any LaTeX package to write citations. Everything is done by Pandoc using custom LaTeX command.

• First approach could work but I am really surprise you would need to do that. Pandoc supports two citation method for latex : natbib and biblatex. Maybe biblatex is what you need for your template ? I would try that.

  Though if you confirm none of them work to write the correct LaTeX syntax expected by the template and journal, then writing your own raw LaTeX content seems the right way. However, you will need to apply the right patch to the Pandoc's template so that the right template content for citation is activated.

Hope it helps

[pat-alt]

Is it included into your .tex output ? Did you opt out Pandoc's citeproc in this case ?

Yes to both, but still no references show up.

Pandoc supports two citation method for latex : natbib and biblatex. Maybe biblatex is what you need for your template ?

I've tried that as well now, but then I get the following error:

finding package for splncs04.dbx
finding package for biblatex-dm.cfg
finding package for splncs04.bbx
ERROR: 
compilation failed- no matching packages
Package biblatex Error: Style 'splncs04' not found.

See the biblatex package documentation for explanation.
Type  H <return>  for immediate help.
 ...                                              
                                                  
l.16290 \RequireBibliographyStyle{\blx@bbxfile}

Apparently, the splncs04.bst uses neither natbib nor biblatex (see this answer on SO).

[cderv]

The only version of splnc04.bst that I could find online claims not to need any additional packages like cite or natbib.

I saw that in your link ☝️

This would explain the problem. Then I guess you need to opt-out citeproc in Pandoc, and you need to tweak templates and maybe play with Lua filter to have Pandoc write the correct LaTeX syntax.

Not sure why "a Lua filter to ensure that @mycitation2025 gets converted to \cite{mycitation2025} and then just include \bibliography{bibliography}" does not work if you get everything as expected in your .tex file 🤷‍♂️

[pat-alt]

@cderv @mcanouil sorry to bug you again, but together with @abuszydlik we have made some progress on this extension. We are hopeful that with some additional guidance from your side we can resolve remaining issues before the submission deadline on March 14. We are also in touch with the conference organizers about what we believe are issues on their end. Beyond that, we think that the extension might ultimately serve as a general extension for Springer Lecture Notes in Computer Science, so it should be of broader use to the community.

Progress

We have made the following progress:

1. Adjusted a publicly available CSL file to style bibliography, though minor issues remain (open relevant issue(s) on our repo)
2. Turned the template into a project+format extension as suggested by @mcanouil in a related discussion (open related discussion)

Remaining Issues

The remaining are collected in a tracking issue on our repo, which I'll link here: open the tracking issue on pat-alt/quarto-ecml. I'll list specific issues below in order of importance (decreasing) without going into details which can be found when following the links:

1. Line spacing between header and body slightly off pat-alt/quarto-ecml#3

Here, I am particularly clueless. I verified that the text width is correct and noticed that the LaTeX template tends to introduce hyphens when Quarto does not.

2. Sort out bibliography through CSL and .bst pat-alt/quarto-ecml#7
3. Quarto theorem environments are not working pat-alt/quarto-ecml#1
4. quarto use template renames template.qmd file and copies output files pat-alt/quarto-ecml#5
5. quarto add does not add lua filter pat-alt/quarto-ecml#4

If helpful, we're happy to expand on specific issues that you think you might be able to help us with. Any additional guidance you may able to provide would be very much appreciated.

Many thanks!