Null sign

The null sign (∅) is often used in mathematics for denoting the empty set.

The same letter in linguistics represents zero, the lack of an element.

Similar letters and symbols include the following: In mathematics, the null sign (∅) denotes the empty set.

The latter two symbols were introduced by the Bourbaki group (specifically André Weil) in 1939, inspired by the letter Ø in the Danish and Norwegian alphabets (and not related in any way to the Greek letter Φ).

In linguistics, the null sign is used to indicate the absence of an element, such as a phoneme or morpheme.

The verb endings of EModE was summarised in the table below by Roger Lass:[3]