Editing Sheffer stroke (section)

==Alternative notations and names==
[[Charles Sanders Peirce|Peirce]] was the first to show the functional completeness of non-conjunction (representing this as <math>\overline{\curlywedge}</math>) but didn't publish his result.<ref name="peirce1880">{{cite encyclopedia |last1=Peirce |first1=C. S. |title=A Boolian Algebra with One Constant |encyclopedia=Collected Papers of Charles Sanders Peirce, Volume IV The Simplest Mathematics |editor1-last=Hartshorne |editor1-first=C. |editor2-last=Weiss |editor2-first=P. |orig-date=1880 |date=1933 |pages=13–18 |location=Massachusetts |publisher=Harvard University Press}}</ref><ref name="peirce1902">{{cite encyclopedia |last1=Peirce |first1=C. S. |title=The Simplest Mathematics |encyclopedia=Collected Papers of Charles Sanders Peirce, Volume IV The Simplest Mathematics |editor1-last=Hartshorne |editor1-first=C. |editor2-last=Weiss |editor2-first=P. |orig-date=1902 |date=1933 |pages=189–262 |location=Massachusetts |publisher=Harvard University Press}}</ref> Peirce's editor added <math>\overline{\curlywedge}</math>) for non-disjunction.<ref name="peirce1902"/>

In 1911, {{ill|Stamm|pl|Edward Bronisław Stamm}} was the first to publish a proof of the completeness of non-conjunction, representing this with <math>\sim</math> (the '''Stamm hook''')<ref name="zach2023">{{cite web |last1=Zach |first1=R. |title=Sheffer stroke before Sheffer: Edward Stamm |url=https://richardzach.org/2023/02/sheffer-stroke-before-sheffer-edward-stamm/ |date=18 February 2023|access-date=2 July 2023}}</ref> and non-disjunction in print at the first time and showed their functional completeness.<ref name="Stamm_1911"/>

In 1913, [[Henry Maurice Sheffer|Sheffer]] described non-disjunction using <math>\mid</math> and showed its functional completeness. Sheffer also used <math>\wedge</math> for non-disjunction.<ref name="zach2023" /> Many people, beginning with [[Jean Nicod|Nicod]] in 1917, and followed by [[Alfred North Whitehead|Whitehead]], [[Bertrand Russell|Russell]] and many others{{Who|date=May 2025}}, mistakenly thought Sheffer had described non-conjunction using <math>\mid</math>, naming this symbol the Sheffer stroke.{{Citation needed|date=May 2025}}

In 1928, [[David Hilbert|Hilbert]] and [[Wilhelm Ackermann|Ackermann]] described non-conjunction with the operator <math>/</math>.<ref name="hilbert-ackermann1928">{{cite book |last1=Hilbert |first1=D. |last2=Ackermann |first2=W. |title=Grundzügen der theoretischen Logik |edition=1 |date=1928 |publisher=Verlag von Julius Springer |location=Berlin |page=9 |language=German}}</ref><ref name="hilbert-ackermann1950">{{cite book |last1=Hilbert |first1=D. |last2=Ackermann |first2=W. |editor1-last=Luce |editor1-first=R. E. |translator1-last=Hammond |translator1-first=L. M. |translator2-last=Leckie |translator2-first=G. G. |translator3-last=Steinhardt |translator3-first=F. |title=Principles of Mathematical Logic |date=1950 |publisher=Chelsea Publishing Company |location=New York |page=11}}</ref>

In 1929, [[Jan Łukasiewicz|Łukasiewicz]] used <math>D</math> in <math>Dpq</math> for non-conjunction in his [[Polish notation]].<ref name="lukasiewicz1929">{{cite book |last1=Łukasiewicz |first1=J. |title=Elementy logiki matematycznej |orig-date=1929|date=1958 |location=Warszawa |publisher=Państwowe Wydawnictwo Naukowe |edition=2 |language=Polish}}</ref>

An alternative notation for non-conjunction is <math>\uparrow</math>. It is not clear who first introduced this notation, although the corresponding <math>\downarrow</math> for non-disjunction was used by Quine in 1940.<ref name="quine1940">{{cite book |last1=Quine |first1=W. V |title=Mathematical Logic |date=1981 |orig-date=1940 |publisher=Harvard University Press |location=Cambridge, London, New York, New Rochelle, Melbourne and Sydney |edition=Revised |page=45}}</ref>