Turned A (capital: Ɐ, lowercase: ɐ, math symbol ∀) is a letter and

symbol A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different conc ...

based upon the letter A.

Modern Usage

* Lowercase ɐ (in Roman or two story form) is used in the

International Phonetic Alphabet The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic notation based primarily on the Latin script. It was devised by the International Phonetic Association in the late 19th century as a standardized representation ...

to identify the

near-open central vowel The near-open central vowel, or near-low central vowel, is a type of vowel sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is , a rotated lowercase double-barrelled letter a. ...

. This is not to be confused with the ''turned

alpha Alpha (uppercase , lowercase ; grc, ἄλφα, ''álpha'', or ell, άλφα, álfa) is the first letter of the Greek alphabet. In the system of Greek numerals, it has a value of one. Alpha is derived from the Phoenician letter aleph , whi ...

'' or ''turned script a'', ɒ, which is used in the IPA for the open back rounded vowel. * The logical symbol ∀, has the same shape as a

sans-serif In typography and lettering, a sans-serif, sans serif, gothic, or simply sans letterform is one that does not have extending features called " serifs" at the end of strokes. Sans-serif typefaces tend to have less stroke width variation than s ...

capital turned A. It is used to represent

universal quantification In mathematical logic, a universal quantification is a type of quantifier, a logical constant which is interpreted as "given any" or "for all". It expresses that a predicate can be satisfied by every member of a domain of discourse. In other ...

in predicate logic, where it is typically read as "for all". It was first used in this way by Gerhard Gentzen in 1935, by analogy with Giuseppe Peano's turned E notation for

existential quantification In predicate logic, an existential quantification is a type of quantifier, a logical constant which is interpreted as "there exists", "there is at least one", or "for some". It is usually denoted by the logical operator symbol ∃, which, ...

and the later use of Peano's notation by

Bertrand Russell Bertrand Arthur William Russell, 3rd Earl Russell, (18 May 1872 – 2 February 1970) was a British mathematician, philosopher, logician, and public intellectual. He had a considerable influence on mathematics, logic, set theory, linguistics, a ...

. * In traffic engineering it is used to represent flow, the number of units (vehicles) passing a point in a unit of time. * It may also be used in unit rates.

Historical Usage

File:Turned A in Edward Lhuyd, Archaeologia Britannica, 1707, p. 226.png , Turned a presented in Edward Lhuyd’s ''Archaeologia Britannica'', 1707. File:Turned A in William Pryce, Archaeologia Cornu-Britannica, 1790, p. 1.png , Turned a in William Pryce’s ''Archaeologia Cornu-Britannica'', 1790. It was used in the 18th century by Edward Lhuyd and William Pryce as a phonetic character for the

Cornish language Cornish (Standard Written Form: or ) , is a Southwestern Brittonic language of the Celtic language family. It is a revived language, having become extinct as a living community language in Cornwall at the end of the 18th century. However, ...

. In their books, both Ɐ and ɐ have been used. It was used in the 19th century by

Charles Sanders Peirce Charles Sanders Peirce ( ; September 10, 1839 – April 19, 1914) was an American philosopher, logician, mathematician and scientist who is sometimes known as "the father of pragmatism". Educated as a chemist and employed as a scientist for ...

as a logical symbol for 'un-American' ("unamerican"). According to the principle of

acrophony Acrophony (; Greek: ἄκρος ''akros'' uppermost + φωνή ''phone'' sound) is the naming of letters of an alphabetic writing system so that a letter's name begins with the letter itself. For example, Greek letter names are acrophonic: the name ...

, the letter A originated from the Proto-Sinatic alphabet as a symbol representing the head of an ox or cow (

aleph Aleph (or alef or alif, transliterated ʾ) is the first letter of the Semitic abjads, including Phoenician , Hebrew , Aramaic , Syriac , Arabic ʾ and North Arabian 𐪑. It also appears as South Arabian 𐩱 and Ge'ez . These lett ...

), its orientation and original meaning having been lost over time. The turned A symbol restores the letter to a more easily recognizable

logographic In a written language, a logogram, logograph, or lexigraph is a written character that represents a word or morpheme. Chinese characters (pronounced '' hanzi'' in Mandarin, '' kanji'' in Japanese, '' hanja'' in Korean) are generally logograms ...

representation of an ox's head. is used in the

Uralic Phonetic Alphabet The Uralic Phonetic Alphabet (UPA) or Finno-Ugric transcription system is a phonetic transcription or notational system used predominantly for the transcription and reconstruction of Uralic languages. It was first published in 1901 by Eemil Nes ...

Encodings

References

{{Latin script, acapital turned A. It is used to represent universal quantification in predicate logic, where it is typically read as "for all". In traffic engineering it is used to represent flow, the number of units (vehicles) passing a point in a unit of time. It may also be used in unit rates. <- what human beings want- to know what it means Logic symbols A Phonetic transcription symbols

Modern Usage

Historical Usage

Encodings

See also

References