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Math Symbol for IFF

Date: 06/18/2003 at 10:11:48
From: Jim Williams
Subject: Mathematical symbol

Is there a mathematical symbol for the term "if and only if"?

Thank you,
Jim Williams


Date: 06/18/2003 at 11:58:53
From: Doctor Douglas
Subject: Re: Mathematical symbol

Hi Jim,

thanks for writing to the Math Forum.

The symbol

   <->       (a double-headed arrow)

is sometimes used in logic to mean "if and only if."  

More generally, one often abbreviates "if and only if" as "iff."
For example:  Show that AB = 0 iff (A=0 or B=0).
 
- Doctor Douglas, The Math Forum
  http://mathforum.org/dr.math/ 
Associated Topics:
High School Logic

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