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 transcription, phonetic notation based primarily on the Latin script. It was devised by the International Phonetic Association in the late 19th century as a standa ...

to identify the near-open central vowel. 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 , whic ...

'' or ''turned script a'', ɒ, which is used in the IPA for the

open back rounded vowel The open back rounded vowel, or low back rounded vowel, is a type of vowel sound, used in some spoken languages. The symbol in the International Phonetic Alphabet that represents this sound is . It is called "turned script ''a''", being a rotated ...

. * 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 seri ...

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 ...

predicate logic First-order logic—also known as predicate logic, quantificational logic, and first-order predicate calculus—is a collection of formal systems used in mathematics, philosophy, linguistics, and computer science. First-order logic uses quantifie ...

, where it is typically read as "for all". It was first used in this way by

Gerhard Gentzen Gerhard Karl Erich Gentzen (24 November 1909 – 4 August 1945) was a German mathematician and logician. He made major contributions to the foundations of mathematics, proof theory, especially on natural deduction and sequent calculus. He died ...

in 1935, by analogy with

Giuseppe Peano Giuseppe Peano (; ; 27 August 1858 – 20 April 1932) was an Italian mathematician and glottologist. The author of over 200 books and papers, he was a founder of mathematical logic and set theory, to which he contributed much notation. The sta ...

turned E Turn may refer to: Arts and entertainment Dance and sports * Turn (dance and gymnastics), rotation of the body * Turn (swimming), reversing direction at the end of a pool * Turn (professional wrestling), a transition between face and heel * Turn, ...

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, ...

. * 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 Edward Lhuyd FRS (; occasionally written Llwyd in line with modern Welsh orthography, 1660 – 30 June 1709) was a Welsh naturalist, botanist, linguist, geographer and antiquary. He is also named in a Latinate form as Eduardus Luidius. Life ...

and

William Pryce William Pryce (baptised 1735–1790) was a British medical man, known as an antiquary, a promoter of the Cornish language and a writer on mining in Cornwall. Life He was the son of Dr. Samuel Pryce of Redruth in Cornwall, and Catherine Hill; ...

as a phonetic character for the

Cornish language Cornish (Standard Written Form: or ) , is a Southwestern Brittonic language, Southwestern Brittonic language of the Celtic language family. It is a List of revived languages, revived language, having become Extinct language, extinct as a livin ...

. 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 t ...

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

), 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, a ...

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 Nesto ...

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