The symbol ∅ is available at Unicode point U+2205.[1] It can be coded in HTML as ∅ and as ∅ or as ∅. It can be coded in LaTeX as \varnothing.
Similar letters
Similar letters and symbols include the following:
Greek letter Φ: majuscule U+03A6ΦGREEK CAPITAL LETTER PHI and minuscule U+03C6φGREEK SMALL LETTER PHI are a part of the Greek alphabet. It sometimes take the form of U+03D5ϕGREEK PHI SYMBOL and is used as a sign in different fields of studies. The U+0278ɸLATIN SMALL LETTER PHI is used in the IPA for voiceless bilabial fricative.
Greek letter Θ: majuscule U+0398ΘGREEK CAPITAL LETTER THETA and minuscule U+03B8θGREEK SMALL LETTER THETA are a part of the Greek alphabet. The minuscule is used in the IPA for voiceless dental fricative. The capital letter sometimes are rendered as U+03F4ϴGREEK CAPITAL THETA SYMBOL.
Cyrillic letter Ф: majuscule U+0424ФCYRILLIC CAPITAL LETTER EF and minuscule U+0444фCYRILLIC SMALL LETTER EF are a part of the Cyrillic script. The letter took the place of fita (U+0472ѲCYRILLIC CAPITAL LETTER FITA and U+0473ѳCYRILLIC SMALL LETTER FITA), a letter of Early Cyrillic alphabet in modern usages.
Use in mathematics
In mathematics, the null sign (∅) denotes the empty set. Note that a null set is not necessarily an empty set. Common notations for the empty set include "{}", "∅", and "". 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).[2]
Empty sets are used in set operations. For example:
There are no common elements in the solution; so it should be denoted as:
In linguistics, the null sign is used to indicate the absence of an element, such as a phoneme or morpheme.
Morphology
The English language was a fusional language, this means the language makes use of inflectional changes to convey grammatical meanings. Although the inflectional complexity of English has been largely reduced in the course of development, the inflectional endings can be seen in earlier forms of English, such as the Early Modern English (abbreviated as EModE).
The verb endings of EModE was summarised in the table below by Roger Lass:[3]
^Lass, R. (1999). Phonology and Morphology. In R. Lass (Ed.), The Cambridge History of the English Language: 1476-1776 (Vol. 3, pp. 137-180). Cambridge, UK: Cambridge University Press.