Turned A

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

Not to be confused with Latin turned alpha.

Lowercase ɐ (in two story form) is used in the International Phonetic Alphabet to identify the near-open central vowel. This is not to be confused with the turned alpha or turned script a, ɒ, which is used in the IPA for the open back rounded vowel.

It was used in the 18th century by Edward Lhuyd and William Pryce as a phonetic character for the Cornish language. In their books, both Ɐ and ɐ have been used.[1] It was used in the 19th century by Charles Sanders Peirce as a logical symbol for 'un-American' ("unamerican").[2]

The logical symbol ∀, has the same shape as a sans-serif capital turned A. It is used to represent universal quantification 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 and the later use of Peano's notation by Bertrand Russell.[3] 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.

U+1D44 ᵄ MODIFIER LETTER SMALL TURNED A is used in the Uralic Phonetic Alphabet.[4]

Encodings
Character information
PreviewⱯɐ∀
Unicode nameLATIN CAPITAL LETTER TURNED ALATIN SMALL LETTER TURNED AFOR ALL
Encodingsdecimalhexdecimalhexdecimalhex
Unicode11375U+2C6F592U+02508704U+2200
UTF-8226 177 175E2 B1 AF201 144C9 90226 136 128E2 88 80
Numeric character referenceⱯⱯɐɐ∀∀
Named character reference∀, ∀
Symbol font3422
TeX\forall

See also

References
  1. Michael Everson, Proposal to add Latin letters and a Greek symbol to the UCS, ISO/IEC JTC1/SC2/WG2 N3122 L2/06-266 (2006)
  2. Page 320 in Randall Dipert, "Peirce's deductive logic". In Cheryl Misak, ed. The Cambridge Companion to Peirce. 2004
  3. Miller, Jeff. "Earliest Uses of Symbols of Set Theory and Logic". Earliest Uses of Various Mathematical Symbols.
  4. Everson, Michael; et al. (2002-03-20). "L2/02-141: Uralic Phonetic Alphabet characters for the UCS" (PDF).
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.