Titlesec, runin shape and amsthm

Question

I'm trying to have an old fashioned style of (sub)section numbering as in EGA (Eléments de Géométrie Algébrique, by A.Grothendieck and J.Dieudonné). For a LaTeX written example, see here.

I did it with the use of the titlesec package, and the following problem arrises : if a section has the shape runin and an amsthm environment follows immediately, the environment creates a line break as usual, which I do not want.

Here is a minimal working example :

documentclass{article}

usepackage{titlesec}
usepackage{amsthm}

titleformat{subsection}[runin]{normalsizebfseries}{(thesubsection)}{5pt}{}

newtheorem*{thm}{Theorem}

begin{document}

section{A section}
subsection{}
begin{thm}
  Foo bar.
end{thm}

end{document}

In this MWE, the line break after (1.1) to begin the thm environment : I would like Theorem to be right after (1.1) on the same line.

How can I do that ?

egreg · Accepted Answer

The style is really old fashioned. ;-)

Define thm to share the subsection counter and modify how the theorem headers are printed.

documentclass{article}

usepackage{titlesec}
usepackage{amsthm}

makeatletter
defthmhead#1#2#3{%
  (thmnumber{@upn{#2})@ifnotempty{#1}{ }}%
  thmname{#1}%
  thmnote{ {thethm@notefont(#3)}}}
makeatother

titleformat{subsection}[runin]{normalsizebfseries}{(thesubsection)}{5pt}{}

newtheorem{thm}[subsection]{Theorem}

begin{document}

section{A section}

Some introductory text.

subsection{}
A subsection

begin{thm}
  Foo bar.
end{thm}

begin{thm}[Someone]
  Foo bar.
end{thm}

end{document}

Clément · Answer

I believe the dieudonne package does exactly what you want.
The demo file requires garamondx and gives:

Titlesec, runin shape and amsthm

2 Answers

Add your own answers!

Ask a Question