The abbreviation appeared in print for the first time in Kelley's 1975 book "General Topology" and was apparently invented by the mathematician [Paul Halmos]?. |

In mathematics, logic and computer science, **iff** is used for "if and only if". The corresponding logical symbols are ↔ and ⇔.

The abbreviation appeared in print for the first time in Kelley's 1975 book "General Topology" and was apparently invented by the mathematician [Paul Halmos]?.