Word of the day – iff
I came across today’s word, iff, in the syntax textbook I’m reading at the moment (Introduction to Government and Binding Theory). When I spotted it I thought at first that it was a typo, but have since discovered that it is used in logic to mean “if and only if”.
Iff can also be represented by the following symbols: ↔, ⇔ or ≡
Quite a few other symbols are used in logic, and to some extent in linguistics textbooks on semantics and syntax. They include:
⇒ / → / ⊃ = if … then
¬ / ˜ = not
⊕ / ⊻ = xor (exclusive or)
∀ = for all/any/each
∃ = there exists
⊢ = infers or is derived from
I vaguely remember learning some of these in maths classes many moons ago and still haven’t quite recovered! I tend to skip parts of books and articles that use them.