[Tex/LaTex] Create a “claim” environment

environments

I am writing a quite long proof in a LaTeX file and I would like to create a "claim" environment to put inside said proof. Can someone help me to understand how this can be done, or at least redirect me to some manual or other resource where it is explained?

What I would like precisely is two environments:

claim: similar to theorem, but maybe instead of getting Claim (bold), only underlined.

claimproof: similar to the proof environment, but with a black box at the end, to distinguish its end from the end of the full proof of the theorem.

Best Answer

Requires amssymb for the black square.

\newenvironment{claim}[1]{\par\noindent\underline{Claim:}\space#1}{}
\newenvironment{claimproof}[1]{\par\noindent\underline{Proof:}\space#1}{\hfill $\blacksquare$}

You can edit and use Claim's proof for example, or anything else. Also, adjust the space above and below, if you want.

\begin{claim}
foo
\end{claim}

\begin{claimproof}
foo
\end{claimproof}

enter image description here

ps: Following the suggestion by @barbara beeton, to avoid new lines before the black square, replace the last pair of {} by

{\leavevmode\unskip\penalty9999 \hbox{}\nobreak\hfill\quad\hbox{$\blacksquare$}}

Related Solutions

[Tex/LaTex] How to create a customized environment

I used the thmtools package as a front-end for amsthm in order to define a new Proof environment; the other two environments were created using \newenvironment. The Proof, claim and precondition environments use adjustwidth from the changepage package to increase the left margin. Of course, feel free to make the necessary adjustments according to your needs:

\documentclass{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsthm}
\usepackage{thmtools}
\usepackage{changepage}
\usepackage[nopar]{lipsum}% just to generate some text

\newlength\Thmindent
\setlength\Thmindent{20pt}

\newenvironment{precondition}
  {\par\medskip\adjustwidth{\Thmindent}{}\normalfont\textbf{Preconditions:}\par\nobreak}
  {\endadjustwidth}
\newenvironment{claim}
  {\par\medskip\adjustwidth{\Thmindent}{}\normalfont\textbf{Claim:}}
  {\endadjustwidth}

\declaretheoremstyle[
  spaceabove=0pt,spacebelow=0pt,
  preheadhook=\adjustwidth{\Thmindent}{},
  prefoothook=\endadjustwidth,
  headpunct=:,
  numbered=no,
  qed=\qedsymbol
]{proof}
\declaretheorem[style=proof]{Proof}

\theoremstyle{plain}
\newtheorem{theorem}{Theorem}

\begin{document}

\begin{theorem}
\lipsum[2]
\begin{precondition}
\begin{itemize}
\item $A := \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}$
\item $B := \begin{pmatrix} 2 & 2 \\ 3 & 4 \end{pmatrix}$
\item $n \in \mathbb{N}$
\end{itemize}
\end{precondition}
\begin{claim}
$\sqrt{2}\notin\mathbb{Q}$
\end{claim}
\begin{Proof}
\lipsum[2]
\end{Proof}
\end{theorem}

\end{document}

enter image description here

[Tex/LaTex] Suggestions for nested proofs

You can simply define a new environment subproof that mimics the behavior of proof but uses a filled square instead of the default one.

\newenvironment{subproof}[1][\proofname]{%
  \renewcommand{\qedsymbol}{$\blacksquare$}%
  \begin{proof}[#1]%
}{%
  \end{proof}%
}

You can even give it the optional argument as in

\begin{subproof}[Subproof]

so to print "Subproof" instead of "Proof".

MWE (note the \item after the outer proof to let enumerate start on a new line)

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

\newtheorem{theorem}{Theorem}

\newenvironment{subproof}[1][\proofname]{%
  \renewcommand{\qedsymbol}{$\blacksquare$}%
  \begin{proof}[#1]%
}{%
  \end{proof}%
}

\begin{document}
\begin{theorem}
  Here comes the statement of the Theorem
\end{theorem}
\begin{proof}
  \item
  \begin{enumerate}
    \item Without loss of generality let us assume...
    \item Claim 1: Statement.%
    \begin{subproof}[Subproof]
      Blah blah
    \end{subproof}
    \item Claim 2: Statement.%
    \begin{subproof}
      Blah blah
    \end{subproof}
  \end{enumerate} 
\end{proof}
\end{document}

enter image description here

Best Answer

Related Solutions

[Tex/LaTex] How to create a customized environment

[Tex/LaTex] Suggestions for nested proofs

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