7

What I want are the symbols used in the textbook Theory of group representations and applications of Asom O. Barut and Ryszard Raczka (2n ed.) for semidirect sum and semidirect product. I upload a photo.

enter image description here

I have been looking for in Unicode symbols and i don't find anything, so probably it is going to be diffcult.

Thanks.

Remark. This question have been marked as possible duplicate question. I don't agree with that. I've tried to use Detexify to find my symbol, but it didn't recognize it. Probably I should study The Comprehensive LaTeX Symbol List better, but that is another question. Any of the answers provided in How to look up a symbol or identify a math symbol or character? solves my problem.

7

You can build the symbols yourself.

\documentclass{article}
\usepackage{pict2e}

\makeatletter
\DeclareRobustCommand{\loplus}{\mathbin{\mathpalette\dog@lsemi{+}}}
\DeclareRobustCommand{\lotimes}{\mathbin{\mathpalette\dog@lsemi{\times}}}
\DeclareRobustCommand{\roplus}{\mathbin{\mathpalette\dog@rsemi{+}}}
\DeclareRobustCommand{\rotimes}{\mathbin{\mathpalette\dog@rsemi{\times}}}

\newcommand{\dog@rsemi}[2]{\dog@semi{#1}{#2}{-90,90}}
\newcommand{\dog@lsemi}[2]{\dog@semi{#1}{#2}{270,90}}
\newcommand{\dog@semi}[3]{%
  \begingroup
  \sbox\z@{$\m@th#1#2$}%
  \setlength{\unitlength}{\dimexpr\ht\z@+\dp\z@\relax}%
  \makebox[\wd\z@]{\raisebox{-\dp\z@}{%
    \begin{picture}(1,1)
    \linethickness{\variable@rule{#1}}
    \roundcap
    \put(0.5,0.5){\makebox(0,0){\raisebox{\dp\z@}{$\m@th#1#2$}}}
    \put(0.5,0.5){\arc[#3]{0.5}}
    \end{picture}%
  }}%
  \endgroup
}
\newcommand{\variable@rule}[1]{%
  \fontdimen8  
  \ifx#1\displaystyle\textfont3\else
    \ifx#1\textstyle\textfont3\else
      \ifx#1\scriptstyle\scriptfont3\else
        \scriptscriptfont3\relax
  \fi\fi\fi
}
\makeatother

\begin{document}

$A\roplus B\rotimes C\loplus D \lotimes E$

$\scriptstyle \roplus\rotimes\loplus\lotimes$

\end{document}

enter image description here

However, note that the standard \oplus and \otimes are lighter than + and \times, so you may want to redefine also them in a similar way, using the full circle.

13

I have just found it. It is defined in stix package, as: \oplusrhrim and \otimesrhrim.

enter image description here

  • Notice that many authors (ab)use the $\ltimes$ and $\rtimes$ symbols for that (mainly because issues with the interplay between stix and amsmath, see section 2.2 of the stix manual). – marmot Feb 16 '18 at 19:50
  • I thought \rtimes and \ltimes were the snatdard symbols. They aren't the usual? – Dog_69 Feb 16 '18 at 20:03
  • What do you mean by "standard"? They come with a vertical bar on the either left- or right-hand side, and thus resemble your symbols, and they are widely used in the literature (even though the one you found look more like the original ones). – marmot Feb 16 '18 at 20:15
  • What I wanted to say is that I thought the ''canonical'' to denote the semidirect product was the \rtimes, for example in Wikipedia's article. And that until Barut and Raczka's book, I'd not seen these symbols. But I agree with you. From my point of view, stix's symbols seems more natural or ''correct''. – Dog_69 Feb 16 '18 at 21:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.