Existential graph

An existential graph is a type of diagrammatic or visual notation for logical expressions, created by Charles Sanders Peirce, who wrote on graphical logic as early as 1882,^[1] and continued to develop the method until his death in 1914. They include both a separate graphical notation for logical statements and a logical calculus, a formal system of rules of inference that can be used to derive theorems.

^ Peirce, C. S., "[On Junctures and Fractures in Logic]" (editors' title for MS 427 (the new numbering system), Fall–Winter 1882), and "Letter, Peirce to O. H. Mitchell" (L 294, 21 December 1882), Writings of Charles S. Peirce, v. 4, "Junctures" on pp. 391–393 (Google preview) and the letter on pp. 394–399 (Google preview). See Sowa, John F. (1997), "Matching Logical Structure to Linguistic Structure", Studies in the Logic of Charles Sanders Peirce, Nathan Houser, Don D. Roberts, and James Van Evra, editors, Bloomington and Indianapolis: Indiana University Press, pp. 418–444, see 420, 425, 426, 428.

[1] Peirce, C. S., "[On Junctures and Fractures in Logic]" (editors' title for MS 427 (the new numbering system), Fall–Winter 1882), and "Letter, Peirce to O. H. Mitchell" (L 294, 21 December 1882), Writings of Charles S. Peirce, v. 4, "Junctures" on pp. 391–393 (Google preview) and the letter on pp. 394–399 (Google preview). See Sowa, John F. (1997), "Matching Logical Structure to Linguistic Structure", Studies in the Logic of Charles Sanders Peirce, Nathan Houser, Don D. Roberts, and James Van Evra, editors, Bloomington and Indianapolis: Indiana University Press, pp. 418–444, see 420, 425, 426, 428.

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