[Tex/LaTex] thmtools declaration for theorem and proof.

formattingthmtools

I'm using thmtools to specify the theorem and proof environments. The problem that arises is that I want my theorems stated in italics and my proofs in non-italic. The following is my initial setup:

\documentclass{report}

\usepackage{amsfonts, amssymb, amsthm}
\usepackage{mathtools}
\usepackage{undertilde}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{hyperref}

\usepackage{thmtools}
\declaretheoremstyle[
    spaceabove=-6pt, 
    spacebelow=6pt, 
    headfont=\normalfont\bfseries, 
    bodyfont = \normalfont,
    postheadspace=1em, 
    qed=$\blacksquare$, 
    headpunct={:}]{mystyle} 
\declaretheorem[name={Proof}, style=mystyle, unnumbered]{Proof}

\declaretheoremstyle[
    spaceabove=6pt, 
    spacebelow=6pt, 
    headfont=\normalfont\bfseries,
    notefont=\mdseries\bfseries, 
    notebraces={(}{)}, 
    bodyfont=\normalfont\itshape,
    postheadspace=1em,
    headpunct={:}]{mystyle}
\declaretheorem[name={Theorem}, style=mystyle,numberwithin=section]{thm}

as with the bodyfont, I've declared the theorem statements to be italic. I have not done so for the proofs, nevertheless, both the theorem and proof are stated in italics.

Best Answer

You're declaring twice the style mystyle, once for Proof and second for Theorem. Only the last one is remmembered. You must change one of style names and apply the change is corresponding \declaretheorem definition.

\documentclass{report}

\usepackage{amsfonts, amssymb, amsthm}
\usepackage{mathtools}
\usepackage{undertilde}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{hyperref}

\usepackage{thmtools}
\declaretheoremstyle[
    spaceabove=-6pt, 
    spacebelow=6pt, 
    headfont=\normalfont\bfseries, 
    bodyfont = \normalfont,
    postheadspace=1em, 
    qed=$\blacksquare$, 
    headpunct={:}]{myproofstyle} %<---- change this name
\declaretheorem[name={Proof}, style=myproofstyle, unnumbered]{Proof}

\declaretheoremstyle[
    spaceabove=6pt, 
    spacebelow=6pt, 
    headfont=\normalfont\bfseries,
    notefont=\mdseries\bfseries, 
    notebraces={(}{)}, 
    bodyfont=\normalfont\itshape,
    postheadspace=1em,
    headpunct={:}]{mystyle}
\declaretheorem[name={Theorem}, style=mystyle,numberwithin=section]{thm}

\begin{document}

\begin{thm}
Body of my first theorem
\end{thm}

\begin{Proof}
This proves my first theorem
\end{Proof}

\end{document}

enter image description here

Related Solutions

[Tex/LaTex] thmtools: How to prevent pagebreak between theorem and proof

Given that the theorem and proof environments are quite separate, it's indeed a bit tricky to forbid categorically all pagebreaks between them. All I can suggest is that you load the package needspace and insert the command

\Needspace{3\baselineskip}

close to the end of the statement of the theorem/corollary/whatever; note the uppercase N at the start of the macro. According to the manual of the needspace package, the command "\Needspace{} is less efficient [than \needspace{}] but reserves the requested space exactly. It should only be used between paragraphs." Given that you're basically facing this situation, you may want to give it a try.

You'll probably have to practice a bit to determine the best placement of this command and the number of baseline skips you require in order to always get at least two lines of the proof statement to show up on the same page as the associated theorem.

[Tex/LaTex] Define proof environment in thmtools

The best way I've found is to redefine the proof environment, that is, add the following lines in your preamble:

\makeatletter
\renewenvironment{proof}[1][\proofname]{\par
  \pushQED{\qed}%
  \normalfont \topsep6\p@\@plus6\p@\relax
  \trivlist
  \item[\hskip\labelsep
        \color{section_color}\sffamily\bfseries
    #1\@addpunct{.}]\ignorespaces
}{%
  \popQED\endtrivlist\@endpefalse
}
\makeatother

MWE

\documentclass{article}

\usepackage{color}
\definecolor{section_color}{rgb}{0.35,0.0,0}
\definecolor{MyGray}{rgb}{0.96,0.97,0.98}

\usepackage{amsthm,thmtools}

% defining common style
\declaretheoremstyle[
spaceabove=6pt, spacebelow=6pt,
headfont=\color{section_color}\sffamily\bfseries,
notefont=\mdseries, notebraces={(}{)},
bodyfont=\normalfont,
postheadspace=1em,
qed=,
]{mystyle}

% defining theorem environment
\declaretheorem[
style=mystyle,
shaded={bgcolor=MyGray,padding=2mm,textwidth=0.98\textwidth}
]{theorem}

% defining claim environment
\declaretheorem[
sibling=theorem,
style=mystyle,
shaded={bgcolor=MyGray,padding=2mm,textwidth=0.98\textwidth}
]{claim}

\makeatletter
\renewenvironment{proof}[1][\proofname]{\par
  \pushQED{\qed}%
  \normalfont \topsep6\p@\@plus6\p@\relax
  \trivlist
  \item[\hskip\labelsep
        \color{section_color}\sffamily\bfseries
    #1\@addpunct{.}]\ignorespaces
}{%
  \popQED\endtrivlist\@endpefalse
}
\makeatother

\begin{document}
%title{Thmtools Example}

\begin{theorem}[Euler's identity]
$e^{i\pi} + 1 = 0$
\end{theorem}

\begin{proof}
Use Euler's formula $e^{ix} = \cos x + i\sin x$.
\end{proof}

\begin{proof}[Proof of Fermat's Last Theorem]
Ask Andrew Wiles.
\end{proof}

\end{document}

Output:

enter image description here

If the additional extra spacing in the margins used for theorems and claims should also be used for proofs, you can change the above redefinition to (thanks to Gonzalo Medina for suggesting it)

\makeatletter
\renewenvironment{proof}[1][\proofname]{\par
  \pushQED{\qed}%
  \normalfont \topsep6\p@\@plus6\p@\relax
  \list{}{\leftmargin=1.25mm\itemindent=20pt\linewidth=0.975\textwidth%
  \item[\hskip\labelsep
        \color{section_color}\sffamily\bfseries
   #1\@addpunct{.}]\ignorespaces}
}{%
  \popQED\endlist\@endpefalse
}
\makeatother

and you will obtain

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] thmtools: How to prevent pagebreak between theorem and proof

[Tex/LaTex] Define proof environment in thmtools

Related Question