The Math Forum

Ask Dr. Math - Questions and Answers from our Archives
Associated Topics || Dr. Math Home || Search Dr. Math

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 
Associated Topics:
High School Logic

Search the Dr. Math Library:

Find items containing (put spaces between keywords):
Click only once for faster results:

[ Choose "whole words" when searching for a word like age.]

all keywords, in any order at least one, that exact phrase
parts of words whole words

Submit your own question to Dr. Math

[Privacy Policy] [Terms of Use]

Math Forum Home || Math Library || Quick Reference || Math Forum Search

Ask Dr. MathTM
© 1994- The Math Forum at NCTM. All rights reserved.