Steve Crawford <scrawford@pinpointresearch.com> writes:
> On 04/15/2014 05:36 PM, Andrew Dunstan wrote:
>> On 04/15/2014 06:26 PM, Thom Brown wrote:
>>> Yeah, apparently those are intentional, and mean "if and only if"
>> This is a reasonably common idiom, or used to be.
> If it has fallen into disuse the news has failed to reach me:
> http://en.wikipedia.org/wiki/If_and_only_if
> http://www.mathwords.com/i/if_and_only_if.htm
> http://mathworld.wolfram.com/Iff.html
The last discussion about this suggested that non-English speakers
might be familiar with other abbreviations for the concept.
But anyway, yes, those are not typos.
regards, tom lane