What does this mean? Whats the difference between IFF and IF?

  • #1
353
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What does this mean? Whats the difference between IFF and IF?
 

Answers and Replies

  • #3
mathman
Science Advisor
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What does this mean? Whats the difference between IFF and IF?
Logical implication A -> B can be expressed as if A then B.

A -> B and B -> A can be expressed as iff A then B.
 
  • #4
353
1


Logical implication A -> B can be expressed as if A then B.

A -> B and B -> A can be expressed as iff A then B.

Oh, I see now.

A<->B is iff

and A->B is if
 
  • #5
795
7


Oh, I see now.

A<->B is iff

and A->B is if

Another way to think about it is that [itex]A \Leftrightarrow B[/itex] means that [itex]A[/itex] and [itex]B[/itex] have the same truth value. Either both are true or both are false.

If you are asked to do a proof of an IFF statement, you should break it down into two proofs: one of [itex]A \Rightarrow B[/itex] and the other of [itex]B \Rightarrow A[/itex]. Typically one direction will be easier than the other.
 

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