An odd behaviour when I use center environment, itemize/enumerate environment and braced \item as the first item

Question

So, I'm coding my note while I run into the following odd behaviour. So, if I first use \begin{center} \end{center} to wrap my contents, and create a list inside using \begin{itemize} \end{itemize}, and further use braces to wrap my first {\item test}, then there will be no item bullet for my second item and the item separation between the first and second items will be smaller than the usual one. Changing the environment from itemize to enumerate then tells me that this is because now the labels of the second and third items are printed together. I want to know how this happens, and maybe further, how to fix this. I'm using the newest TeXLive 2021 in a macOS 10.15.7 Intel computer. Both pdfLaTeX and XeLaTeX engines give the same output.

MWE

\documentclass{book}
\usepackage{lipsum}
\begin{document}
\fbox{\bfseries enumerate with braced item}
\begin{enumerate}
    {\item test}
    \item second item
    \item third item
\end{enumerate}
\fbox{\bfseries enumerate between center environment}
\begin{center}
    \begin{enumerate}
        \item test
        \item second item
        \item third item
    \end{enumerate}
\end{center}
\fbox{\bfseries enumerate with braced item and between center environment}
\begin{center}
    \begin{enumerate}
        {\item test}
        \item second item
        \item third item
    \end{enumerate}
\end{center}
\fbox{\bfseries Let me try to change \texttt{baselinestretch}}
\renewcommand{\baselinestretch}{3}
\begin{center}
    \begin{enumerate}
        {\item test}
        \item second item
        \item third item
    \end{enumerate}
\end{center}
\renewcommand{\baselinestretch}{1}
\fbox{\bfseries What if the braced one is not the first?}
\begin{center}
    \begin{enumerate}
        \item first item
        {\item test}
        \item second item
        \item third item
    \end{enumerate}
\end{center}
\fbox{\bfseries What if I use \texttt{centering}?}
{\centering\begin{enumerate}
        {\item test}
        \item second item
        \item third item
    \end{enumerate}}
\clearpage
\fbox{\bfseries An even odder result}
\fbox{\small First list}
\begin{center}
    \begin{enumerate}
        {\item test}
        \item second item
    \end{enumerate}
\end{center}


\fbox{\small The following list}
\begin{center}
    \begin{enumerate}
        \item first item
        \item second item
        \item third item
    \end{enumerate}
\end{center}


\fbox{\bfseries How about some text in between?}
\fbox{\small First list}
\begin{center}
    \begin{enumerate}
        {\item test}
        \item second item
    \end{enumerate}
\end{center}

\lipsum[1]


\fbox{\small The following list}
\begin{center}
    \begin{enumerate}
        \item first item
        \item second item
        \item third item
    \end{enumerate}
\end{center}


\end{document}

PDF output (attention that in the following output, the item test is always braced, and other items always not)

.log file

This is pdfTeX, Version 3.141592653-2.6-1.40.22 (TeX Live 2021) (preloaded format=pdflatex 2021.10.17)  20 OCT 2021 05:23
entering extended mode
 restricted \write18 enabled.
 file:line:error style messages enabled.
 %&-line parsing enabled.
**test
(./test.tex
LaTeX2e <2020-10-01> patch level 4
L3 programming layer <2021-02-18> (/usr/local/texlive/2021/texmf-dist/tex/latex/base/book.cls
Document Class: book 2020/04/10 v1.4m Standard LaTeX document class
(/usr/local/texlive/2021/texmf-dist/tex/latex/base/bk10.clo
File: bk10.clo 2020/04/10 v1.4m Standard LaTeX file (size option)
)
\c@part=\count179
\c@chapter=\count180
\c@section=\count181
\c@subsection=\count182
\c@subsubsection=\count183
\c@paragraph=\count184
\c@subparagraph=\count185
\c@figure=\count186
\c@table=\count187
\abovecaptionskip=\skip47
\belowcaptionskip=\skip48
\bibindent=\dimen138
) (/usr/local/texlive/2021/texmf-dist/tex/latex/lipsum/lipsum.sty (/usr/local/texlive/2021/texmf-dist/tex/latex/l3kernel/expl3.sty
Package: expl3 2021-02-18 L3 programming layer (loader) 
 (/usr/local/texlive/2021/texmf-dist/tex/latex/l3backend/l3backend-pdftex.def
File: l3backend-pdftex.def 2021-03-18 L3 backend support: PDF output (pdfTeX)
\l__color_backend_stack_int=\count188
\l__pdf_internal_box=\box47
)) (/usr/local/texlive/2021/texmf-dist/tex/latex/l3packages/xparse/xparse.sty (/usr/local/texlive/2021/texmf-dist/tex/latex/l3packages/xparse/xparse-2020-10-01.sty (/usr/local/texlive/2021/texmf-dist/tex/latex/l3packages/xparse/xparse-generic.tex)))
Package: lipsum 2021-03-03 v2.3 150 paragraphs of Lorem Ipsum dummy text
 (/usr/local/texlive/2021/texmf-dist/tex/latex/lipsum/lipsum.ltd.tex
File: lipsum.ltd.tex 2021-03-03 v2.3 The Lorem ipsum dummy text
)) (./test.aux)
\openout1 = `test.aux'.
LaTeX Font Info:    Checking defaults for OML/cmm/m/it on input line 711.
LaTeX Font Info:    ... okay on input line 711.
LaTeX Font Info:    Checking defaults for OMS/cmsy/m/n on input line 711.
LaTeX Font Info:    ... okay on input line 711.
LaTeX Font Info:    Checking defaults for OT1/cmr/m/n on input line 711.
LaTeX Font Info:    ... okay on input line 711.
LaTeX Font Info:    Checking defaults for T1/cmr/m/n on input line 711.
LaTeX Font Info:    ... okay on input line 711.
LaTeX Font Info:    Checking defaults for TS1/cmr/m/n on input line 711.
LaTeX Font Info:    ... okay on input line 711.
LaTeX Font Info:    Checking defaults for OMX/cmex/m/n on input line 711.
LaTeX Font Info:    ... okay on input line 711.
LaTeX Font Info:    Checking defaults for U/cmr/m/n on input line 711.
LaTeX Font Info:    ... okay on input line 711.
LaTeX Font Info:    Font shape OT1/cmtt/bx/n' in size &lt;10&gt; not available (Font) Font shapeOT1/cmtt/m/n' tried instead on input line 738.
 [1{/usr/local/texlive/2021/texmf-var/fonts/map/pdftex/updmap/pdftex.map}
] [2
] (./test.aux) ) 
Here is how much of TeX's memory you used:
 630 strings out of 478994
 13217 string characters out of 5858183
 561570 words of memory out of 5000000
 18176 multiletter control sequences out of 15000+600000
 404558 words of font info for 31 fonts, out of 8000000 for 9000
 1141 hyphenation exceptions out of 8191
 71i,5n,75p,194b,161s stack positions out of 5000i,500n,10000p,200000b,80000s
</usr/local/texlive/2021/texmf-dist/fonts/type1/public/amsfonts/cm/cmbx10.pfb></usr/local/texlive/2021/texmf-dist/fonts/type1/public/amsfonts/cm/cmr10.pfb></usr/local/texlive/2021/texmf-dist/fonts/type1/public/amsfonts/cm/cmr9.pfb></usr/local/texlive/2021/texmf-dist/fonts/type1/public/amsfonts/cm/cmtt10.pfb>
Output written on test.pdf (2 pages, 55522 bytes).
PDF statistics:
 27 PDF objects out of 1000 (max. 8388607)
 18 compressed objects within 1 object stream
 0 named destinations out of 1000 (max. 500000)
 1 words of extra memory for PDF output out of 10000 (max. 10000000)

.aux file

\relax 
\gdef \@abspage@last{1}

If insist for me to give a reason. Maybe {\bfseries\item test} is a quite good example where I could use local style command. — Qi Tianluo, Oct 19 '21 at 21:36
\item simply won't work in a group it sets up the paragraph shape for the text using local definitions and the group breaks the processing completely use \item \textbf{test} — David Carlisle, Oct 19 '21 at 21:43
Well you could do that with \bfseries\item test \normalfont too. As you demonstrate adding grouping around arbitrary code can have side effects. center is a list too and starts with \item, and \item is a rather complicated command which is only typeset when the paragraph starts. — Ulrike Fischer, Oct 19 '21 at 21:44
@DavidCarlisle Thanks. Care to expand on "the group breaks the processing"? Or maybe point to me some link? — Qi Tianluo, Oct 19 '21 at 21:59
@UlrikeFischer Sure, I'm aware of this method. Actually, this is exactly the method I use after finding this odd behaviour. "center is a list too and starts with \item", so, you mean that the center environment is written using itemize? — Qi Tianluo, Oct 19 '21 at 22:01
well you demonstrate it here quite well, the list processing is broken and if you remove the group and remove the outer center environment it is fixed. — David Carlisle, Oct 19 '21 at 22:12
lists - Missing bullet when itemize \item content is empty and buried within a group - TeX - LaTeX Stack Exchange — user202729, Oct 20 '21 at 07:26

An odd behaviour when I use center environment, itemize/enumerate environment and braced \item as the first item

0 Answers0