[Tex/LaTex] Need some hints to start with the package amsthm

amsthm

I want to highlight my proposition and i don't need the enumeration for now.

The source file is the following:

\usepackage{amsmath, amssymb, amsthm}

\begin{document}

\begin{theorem}

... bla bla bla, not so interesting ...

\end{theorem}

\end{document}

To compile I use pdflatex, and the reported error is "Environment theorem is undefined".

You have to know that I'm sure that the other math packages are installed (amsmath, amssymb), and secondly my proposition isn't highlighted in the final document.

EDIT:

For highlighting, I wish that the reader can understand almost without reading that a block of text is a theorem, a proposition, and so on… So, what I want is for example, that all the propositions have the same style, all the theorems have the same style (but different from the style of the propositions). And I think that using this package is fast and handy.

Best Answer

Loading amsthm alone it's not enough. You need to declare the theorem structure first, using \newtheorem (or the starred variant for unnumbered structure), as in

\documentclass{article}  
\usepackage{amsmath, amssymb, amsthm}

\newtheorem{theorem}{Theorem}

\begin{document}

\begin{theorem}
A test theorem
\end{theorem}

\end{document}

The result:

enter image description here

\newtheorem has a more complex syntax with two optional (mutually exclusive) arguments allowing control over the counter; refer to the package documentation for details.

Regarding the second part of your question, you mentioned that you want to "highlight" the theorems, but you didn't mention what exactly do you mean by highlighting. Do you want a special formatting such as a background color, a frame? If so, please refer to mdframed or thmtools or tcolorbox. The documentation of each package has example showing how to get fancy designs for theorems and in this site there are numerous examples of the use of those packages to produce theorem-like structures with several kinds of decorations: you could have a look, for example, at

Related Solutions

[Tex/LaTex] How to change the numbering style of theorems based on the section number using amsthm

You could use

\renewcommand{\theprop}{\arabic{section}.\arabic{prop}}

[Tex/LaTex] Remove vertical space around theorems

Firstly, below skip should be positive, negative values are ignored. You can clear the spacing provided as standard by writing

\makeatletter
\def\thm@space@setup{\thm@preskip=0pt
\thm@postskip=0pt}
\makeatother

before your \newtheoremstyle. You can adjust this by changing the values 0pt or using the parameters in the \newtheoremstyle.

Try

\newenvironment{pf}{\noindent\textit{Proof.}\begin{mdseries}}{\end{mdseries}}

for your proof environment. If this is too simplistic, e.g. if you wish to have the \qed features of the AMS environment, then you can use the following adaption of the AMS proof code

\makeatletter
\newenvironment{pf}[1][\proofname]{\par
  \pushQED{\qed}%
  \normalfont \topsep0\p@\relax
  \trivlist
  \item[\hskip\labelsep\itshape
  #1\@addpunct{.}]\ignorespaces
}{%
  \popQED\endtrivlist\@endpefalse
}
\makeatother

The important point is setting the value of \topsep to zero.

Lastly, the proposition number is wrong because you have asked it to be numbered within thms! You should write

\newtheorem{prop}[thm]{Proposition}

with [thm] placed between the other arugments not at the end.

Here is this all put in to one sample document.

\documentclass{article}

\usepackage{amsthm}

\makeatletter
\def\thm@space@setup{\thm@preskip=0pt
\thm@postskip=0pt}
\makeatother
\newtheoremstyle{newstyle}      
{} %Aboveskip 
{} %Below skip
{\mdseries} %Body font e.g.\mdseries,\bfseries,\scshape,\itshape
{} %Indent
{\bfseries} %Head font e.g.\bfseries,\scshape,\itshape
{.} %Punctuation afer theorem header
{ } %Space after theorem header
{} %Heading

\theoremstyle{newstyle}
\newtheorem{thm}{Theorem}[section]
\newtheorem{prop}[thm]{Proposition}
\newtheorem{lem}{Lemma}
\newtheorem{cor}{Corollary}

\makeatletter
\newenvironment{pf}[1][\proofname]{\par
  \pushQED{\qed}%
  \normalfont \topsep0\p@\relax
  \trivlist
  \item[\hskip\labelsep\itshape
  #1\@addpunct{.}]\ignorespaces
}{%
  \popQED\endtrivlist\@endpefalse
}
\makeatother

\begin{document}
Some text to indicate the spacing.

\begin{thm}
  First theorem, with sufficiently long text so that it spills on to a
  second line.
\end{thm}

Some text to indicate the spacing.  Fill-up text make this spill on to
an extra line.  Fill-up text make this spill on to an extra line.

More text.

\begin{prop}
  A proposition, with sufficiently long text so that it spills on to a
  second line.
\end{prop}

\begin{pf}
  Proof of the proposition with \verb+pf+ environment and sufficiently
  long text so that it spills on to a second line.
\end{pf}

\begin{prop}
  Another proposition, with sufficiently long text so that it spills
  on to a second line.
\end{prop}

\begin{proof}
  The original proof environment and sufficiently long text so that it
  spills on to a second line.
\end{proof}

\end{document}

Sample output

Best Answer

Related Solutions

[Tex/LaTex] How to change the numbering style of theorems based on the section number using amsthm

[Tex/LaTex] Remove vertical space around theorems

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