A special mathematical symbol (supremum of directed set)

Question

I am trying to find a certain mathemtical symbol. It is a \bigvee with an arrowhead as in this picture:

Some authors use this as symbol in domain theory. It denotes the supremum of a set and furthermore states that the set is directed.
I did not find it in the The Comprehensive LaTeX Symbol List.

Answer 1

There are two ways to go (actually three, if you include drawing your symbol with tikz, against which you will find several advocates on this site ;)):

\documentclass[10pt,a4paper]{article}
\usepackage{stmaryrd}
\usepackage{graphicx}

\begin{document}
$A~\setminus\kern-.95ex\nnearrow B$ %This needs the stmaryrd package for the \nnearrow symbol

$\bigvee{}\kern-1.5ex\rotatebox{-30}{$\large\mathbf{\hat{\vphantom{a}}}$}$ %\rotatebox requires the graphicx package
\end{document}

Adjust rotation and kerning as you you wish. :)

Answer 2

Here is a very nice solution which I found on the web, I cannot remember where; I wish I could attribute it properly.

\newcommand{\dirsup}{\mathrel{\setlength{\unitlength}{.7em}\raisebox{-.2em}%
    {\begin{picture}(1,1.5)\put(.5,0){\line(-1,3){.48}}
    \put(.5,0){\vector(1,3){.5}}\end{picture}}}} % directed sup

You can see the symbols side by side at http://www.cs.mcgill.ca/~prakash/dirsup_comparison.pdf:

Answer 3

Probably not as good as the answer already accepted, but possibly useful when rotated a quarter of a circle:

Lightning: ☇ Unicode hexadecimal: 0x2607 In block: Miscellaneous Symbols

See Is there a readymade symbol for a 90 degrees rotated \Bowtie? for rotation code.

Answer 4

Since @CountZero suggested it :-), here is a TikZ version showing a few of the options:

Code:

\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\newcommand{\SupermumDirected}[1][]{%
    \mathbin{\tikz [x=1.4ex,y=1.6ex,line width=.15ex,baseline] 
        \draw [->,#1] (0,1) -- (0.5,0) -- (1,1.25);
    }%
}

\begin{document}
    $A \SupermumDirected B \SupermumDirected[red,-stealth] C \SupermumDirected[blue,-latex] D$
\end{document}