Is there a "contradiction" symbol in some font, somewhere?

Question

Before anyone slates me for this, I have checked detexify and texdoc symbols. Indeed, the latter led me to the following phrase (3rd paragraph of Section 3):

Although there have been many requests on comp.text.tex for a contradiction symbol, the ensuing discussion invariably reveals innummerable ways to represent contradiction in a proof ... Because of the lack of notational consensus, it is probably better to spell out "Contradiction!" than to use a symbol for this purpose.

Normally, I'd agree with this sage advice. Two things prevent me from doing so:

1. In a presentation, brevity is the soul of comprehension.

   That is to say, it is better still to have a funny symbol and to say "Thus we have a contradiction" than to have the long word "Contradiction!" and still say "Thus we have a contradiction".

2. The ellipsis in the above quote lists various symbols that the discussion on comp.text.tex presumably discussed. None of them is correct. The correct contradiction symbol is (something like):

   \ \/ /
    \/\/
    /\/\    
   / /\ \
   

   That is, four diagonal lines, two in each direction. It should also be a bit larger than a "regular" symbol, perhaps more like a \prod or \sum.

So, my question: is there a font with this symbol?

Answer 1

The Unicode symbol "⨳" (U+2A33, it is called "SMASH PRODUCT" for some mysterious reasons) you are looking for is available with modern TeX engines (XeTeX, LuaTeX): You'll have to load the unicode-math package and an appropiate OpenType math font such as XITS Math, then you can access it as \smashtimes.

\documentclass{article}
\usepackage{unicode-math}
\setmathfont{XITS Math}
\begin{document}
    $\smashtimes$
\end{document}

Answer 2

My attempt, based on diabonas' answer and flying sheep's comment:

\documentclass{article}
\usepackage{tikz}

\newcommand{\contradiction}{%
\begin{tikzpicture}[rotate=45,x=0.5ex,y=0.5ex]
\draw[line width=.2ex] (0,2) -- (3,2) (0,1) -- (3,1) (1,3) -- (1,0) (2,3) -- (2,0);
\end{tikzpicture}
}

\begin{document}

Contradiction? \contradiction

\end{document}

Bear with me, I'm a TikZ newbie. =P

Answer 3

Here's a macro that kludges this symbol out of four \times signs:

\newcommand{\contradiction}{{\hbox{%
    \setbox0=\hbox{$\mkern-3mu\times\mkern-3mu$}%
    \setbox1=\hbox to0pt{\hss$\times$\hss}%
    \copy0\raisebox{0.5\wd0}{\copy1}\raisebox{-0.5\wd0}{\box1}\box0
}}}

This macro requires no additional packages or special fonts; everything it uses is plain vanilla LaTeX.

An explanation of how this works: The second line (beginning with \setbox0) creates a box containing a single \times sign and stores this box in register 0; the \mkern commands add a bit of negative space on either side of the \times so that the left and right sides of the box are flush with the edges of the \times symbol. The next line (beginning with \setbox1) creates a similar box in register 1, except that this box has width 0, with the \times symbol centered horizontally (\hss stands for "horizontal stretch or shrink"; putting it on both sides achieves the centering effect). So here the \times symbol actually extends outside the zero-width box, equally far on both sides. The fourth line copies the contents of the box in register 0 to the output, then copies the contents of the box in register 1 to the output after raising it by half of the width of the box in register 0 (i.e., half of the width of the \times sign), then moves the box in register 1 to the output after lowering it by half of the width of the box in register 0, then moves the box in register 0 to the output.

Answer 4

I don't think there's a "correct" symbol for contradiction. I use the symbol you describe (in my handwritten notes) for things along the lines of "contradiction" or "this is obviously wrong" or "aargh I've made a bad mistake somewhere".

If you \usepackage{mathabx}, you can get a nice large cross symbol which you can use to construct the double-cross: something along the lines of

\mbox{\rlap{$\displaystyle\bigtimes$}{$\displaystyle\,\bigtimes$}}

would work.

Answer 5

The symbol is also available in the legacy stix and stix2 packages, as \smashtimes.