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Can someone point me to Unicode and/or LaTeX symbol that's used to indicate that two events are statistically independent? Ideally, it should be possible to produce this symbol in the equation editor in Word 2007.

It should look like a horizontal bar with two vertical bars sticking out, sort of like a simple upside-down π.

Edit: this is the symbol:

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2 Answers 2

up vote 2 down vote accepted

Are you looking for the coproduct symbol ∐? This is the N-ary Coproduct symbol (U+2210) in Unicode, \coprod in LaTeX.

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When I try to add this symbol in Word 2010-2013 I get an empty square box instead of the independence symbol. Any ideas why this happens? I have tried many of the fonts that support this symbol fileformat.info/info/unicode/char/2210/fontsupport.htm –  ECII Jul 5 at 7:15
    
I have no issues with this symbol in Word 2010 on Windows 7 using the Cambria Math font. –  M. Dudley Jul 9 at 11:55

There is no standard symbol for this in LaTex. This symbol is often defined as:

\def\ci{\perp\!\!\!\perp}

You can see it in use on the wikipedia page for Conditional Independence.

If there's such a thing as an 'offical' definition, there's this from the Comprehensive LaTex Symbol List page 106:

Donald Arseneau posted the following \mathpalette-based definition of a probabilistic-independence symbol ⊥⊥ to comp.text.tex in June 2000:

\newcommand\independent{\protect\mathpalette{\protect\independenT}{\perp}}
\def\independenT#1#2{\mathrel{\rlap{$#1#2$}\mkern2mu{#1#2}}}

The \independent macro uses \mathpalette to pass the \independenT helper macro both the current math style and the \perp symbol. \independenT typesets \perp in the current math style, moves two math units to the right, and finally typesets a second—overlapping—copy of \perp, again in the current math style. \rlap, which enables text overlap, is described later on this page.

Frankly, I like the first version better. It might not always render properly in all math fonts, but I can remember it when I need it. Sorry, I don't know how to do this in the equation editor.

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