39
\documentclass{article}
\usepackage{graphicx}

\begin{document}
\vspace{\baselineskip}\noindent
\textbf{THEOREM :} If an operator has both Left Identity and Right Identity then it is \emph{UNIQUE}.
\vspace{\baselineskip}\noindent
\textbf{PROOF :} Let e_{l} is left identity 
                         therefore e_{l} * e_{r} 
                             this implies e_{r}
\end{document}
5
  • 2
    Welcome to TeX.SX! Please make your code compilable, starting with \documentclass{...} and ending with \end{document}. That may seem tedious to you, but think of the extra work it represents for TeX.SX users willing to help you. Help them help you: remove that one hurdle between you and a solution to your problem.
    – Ronny
    Commented Nov 6, 2013 at 10:40
  • It would be nice, if you could explain, what you tried to include the symbols, where they should appear, and whether you need that in more than this small example (because then maybe it's better to use algorithm2e or something like that).
    – Ronny
    Commented Nov 6, 2013 at 11:08
  • i want to write symbol for "therefore"
    – user39495
    Commented Nov 6, 2013 at 11:10
  • 3
    If you are using \vspace font changes or \noindent in a document it is a sign that something is probably wrong. Ideally the markup should just be \begin{theorem} with the spacing and fonts specified elsewhere. Commented Nov 6, 2013 at 11:12
  • 3
    the three dots symbol is $\therefore$ (amssymb package) see texdoc symbols Commented Nov 6, 2013 at 11:14

6 Answers 6

46

As stated in the comments, you get the symbols in mathmode simply by writing them down. Packages like amsmath and amssymb support you.

\documentclass{article}
\usepackage{amsmath}
\usepackage{amssymb}
\newtheorem{theorem}{THEOREM}
\newtheorem{proof}{PROOF}
\begin{document}
\begin{theorem}
If an operator has both Left Identity and
Right Identity then it is \emph{UNIQUE}.
\end{theorem}
\begin{proof}
Let $e_{l}$ is left identity 
$\therefore e_{l} * e_{r} \implies e_{r}$
\end{proof}
\end{document}

enter image description here

7
  • 1
    With a very fierce “don't do it in a printed document”!
    – egreg
    Commented Mar 21, 2015 at 15:57
  • I think you're missing an amsthm somewhere.
    – kahen
    Commented Mar 21, 2015 at 20:31
  • 1
    @kahen Can you explain why? Did you run my example?
    – Johannes_B
    Commented Mar 22, 2015 at 9:49
  • 1
    @user71207 math is for maths, symb is for symbols.
    – Johannes_B
    Commented Mar 14, 2021 at 1:45
  • 1
    @user71207 The AMS is the American Mathematical Society.
    – Johannes_B
    Commented Mar 14, 2021 at 8:10
5

A somewhat larger version of \therefore may be built as:

\dot{.\hspace{.095in}.}\hspace{.5in}

Comparison traditional and larger version:

enter image description here

1
  • 1
    That sort of tricks may be OK for visual rendering but they can be highly undesirable when trying to copy raw text from a generated PDF Commented Dec 29, 2018 at 22:46
4

Initialisation Code:

\def\therefore{\boldsymbol{\text{ }
\leavevmode
\lower0.4ex\hbox{$\cdot$}
\kern-.5em\raise0.7ex\hbox{$\cdot$}
\kern-0.55em\lower0.4ex\hbox{$\cdot$}
\thinspace\text{ }}}

And can then be called on using:

\therefore

Which renders as:

RENDERED THEREFORE

0
3

Maybe you could simply use lualatex and a font which actually has the character:

%!TEX TS-program = lualatex
\documentclass{article}
\usepackage{fontspec}
    \setmainfont{Brill}% just an example -- download at http://www.brill.com/about/brill-fonts
\newtheorem{theorem}{THEOREM}
\newtheorem{proof}{PROOF}
\begin{document}
\begin{theorem}
If an operator has both Left Identity and
Right Identity then it is \emph{UNIQUE}.
\end{theorem}
\begin{proof}
Let $e_{l}$ is left identity 
∴ $e_{l} * e_{r}$ ⇒ $e_{r}$
\end{proof}
\end{document}

enter image description here

0
\documentclass{article}
\usepackage{graphicx}

\usepackage{amssymb}
\usepackage{amsmath}

\begin{document}
\vspace{\baselineskip}\noindent
\textbf{THEOREM :} If an operator has both Left Identity and Right Identity then it is \emph{UNIQUE}.
\vspace{\baselineskip}\noindent
\textbf{PROOF :} Let e\_{l} is left identity 
                         $\therefore$ e\_{l} * e\_{r} 
                             $\implies$ e\_{r}
                             $\Rightarrow$ e\_{r}
\end{document}

The above code will give you the following result. I have added two "implies" symbol in case one of those looks too long.

preliminary

A better formatting for the document would be,

\documentclass{article}
\usepackage{graphicx}

\usepackage{amssymb}
\usepackage{amsmath}

\usepackage{amsthm}
\theoremstyle{definition}
\newtheorem{theorem}{Theorem} % for adding lemma

\begin{document}
\vspace{\baselineskip}\noindent
\begin{theorem}
If an operator has both Left Identity and Right Identity then it is \emph{UNIQUE}.
\end{theorem}

\begin{proof}
Let $e\_l$ is left identity.
\begin{align*}
    \therefore e_l * e_r \\
    \implies e_r \\
    \Rightarrow e_r
\end{align*}
\end{proof}
\end{document}

which will generate the following.

improved

0

Not entirely happy with any of the handmade therefore's proposed above, I thought I would offer this one also that, in my opinion, has a good balance of dot size (in between \bullet and \cdot) and spacing:

\def\therefore{{\tiny$\bullet$}\kern-0.2ex\raisebox{1ex}{\tiny$\bullet$}\kern-0.2ex{\tiny$\bullet$}}

Here is an example:

enter image description here

2
  • you might want to share a rendering of it...
    – 3kstc
    Commented Sep 25, 2020 at 3:26
  • 1
    Add rendering example, I also prefer a bolder therefore
    – rhody
    Commented Nov 4, 2023 at 1:02

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