Sheffer stroke - WikipediaLogical equivalences[edit] The Sheffer stroke of and is the negation of their conjunction Alternative notations and names[edit] Peirce was the first to show the functional completeness of non-conjunction (representing this as ) but didn't publish his result.[2][3] Peirce's editor added ) for non-disjunction[citation needed].[3] In 1911, Stamm was the first to publish a proof of the completeness of
