Ɐ

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

Modern usage

Lowercase ɐ (in Roman or 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.^[1]
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.^[2]

Historical usage

Turned a presented in Edward Lhuyd's Archaeologia Britannica, 1707.
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. In their books, both Ɐ and ɐ have been used.^[3] It was used in the 19th century by Charles Sanders Peirce as a logical symbol for 'un-American' ("unamerican").^[4]

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), its orientation and original meaning having been lost over time. The turned A symbol restores the letter to a more easily recognizable logographic representation of an ox's head.^[5]

U+1D44 ᵄ MODIFIER LETTER SMALL TURNED A is used in the Uralic Phonetic Alphabet.^[6]

Encodings

Character information
Preview	Ɐ		ɐ		∀
Unicode name	LATIN CAPITAL LETTER TURNED A		LATIN SMALL LETTER TURNED A		FOR ALL
Encodings	decimal	hex	dec	hex	dec	hex
Unicode	11375	U+2C6F	592	U+0250	8704	U+2200
UTF-8	226 177 175	E2 B1 AF	201 144	C9 90	226 136 128	E2 88 80
Numeric character reference	Ɐ	Ɐ	ɐ	ɐ	∀	∀
Named character reference					&ForAll;, ∀
Symbol font					34	22
TeX					\forall

References

^ Gibbon, Dafydd; Richard Winski, Roger Moore (1997). "Table A.19: IPA Table (ordered by number) (continued)". Handbook of Standards and Resources for Spoken Language Systems. Walter de Gruyter. p. 679. ISBN 9783110153668.
^ Miller, Jeff. "Earliest Uses of Symbols of Set Theory and Logic". Earliest Uses of Various Mathematical Symbols.
^ Michael Everson, Proposal to add Latin letters and a Greek symbol to the UCS, ISO/IEC JTC1/SC2/WG2 N3122 L2/06-266 (2006)
^ Page 320 in Randall Dipert, "Peirce's deductive logic". In Cheryl Misak, ed. The Cambridge Companion to Peirce. 2004
^ Jensen, Hans (1969). Sign, Symbol, and Script. New York: G.P. Putman's Sons. p. 262. ISBN 9780044000211.
^ Everson, Michael; et al. (2002-03-20). "L2/02-141: Uralic Phonetic Alphabet characters for the UCS" (PDF).

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[1] Gibbon, Dafydd; Richard Winski, Roger Moore (1997). "Table A.19: IPA Table (ordered by number) (continued)". Handbook of Standards and Resources for Spoken Language Systems. Walter de Gruyter. p. 679. ISBN 9783110153668.

[2] Miller, Jeff. "Earliest Uses of Symbols of Set Theory and Logic". Earliest Uses of Various Mathematical Symbols.

[3] Michael Everson, Proposal to add Latin letters and a Greek symbol to the UCS, ISO/IEC JTC1/SC2/WG2 N3122 L2/06-266 (2006)

[4] Page 320 in Randall Dipert, "Peirce's deductive logic". In Cheryl Misak, ed. The Cambridge Companion to Peirce. 2004

[5] Jensen, Hans (1969). Sign, Symbol, and Script. New York: G.P. Putman's Sons. p. 262. ISBN 9780044000211.

[6] Everson, Michael; et al. (2002-03-20). "L2/02-141: Uralic Phonetic Alphabet characters for the UCS" (PDF).

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Modern usage

Historical usage

Encodings

See also

References