Talk:if and only if

Isn't this entry redundant? --Eean 05:05, 25 Dec 2004 (UTC)

Decomposition
The following are common logical equivalents (A and B can also be swapped in each): Composed expressions Decomposed expressions (first phrases are all equivalent as well as second phrases --Bequw → τ 15:29, 20 August 2010 (UTC)
 * 1) A if and only if B
 * 2) A ⇔ B
 * 3) (A is necessary and sufficient for B) / (A is a necessary and sufficient condition for B)
 * 1) (A if B) and (A only if B)
 * 2) (A if B) and (B if A)
 * 3) (if B then A) and (if A then B)
 * 4) (B ⇒ A) and (A ⇒ B)
 * 5) (B ⇒ A) and (B ⇐ A)
 * 6) (A is necessary for B) and (A is sufficient for B)