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An existential graph is a type of diagrammatic or visual notation for logical expressions, proposed by Charles Sanders Peirce, who wrote on graphical logic as early as 1882,〔Peirce, C. S., "(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. 391–3 (Google (preview )) and the letter on pp. 394–9 (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 Indianopolis: Indiana University Press, pp. 418–44, see 420, 425, 426, 428.〕 and continued to develop the method until his death in 1914. ==The graphs== Peirce proposed three systems of existential graphs: * ''alpha'', isomorphic to sentential logic and the two-element Boolean algebra; * ''beta'', isomorphic to first-order logic with identity, with all formulas closed; * ''gamma'', (nearly) isomorphic to normal modal logic. ''Alpha'' nests in ''beta'' and ''gamma''. ''Beta'' does not nest in ''gamma'', quantified modal logic being more than even Peirce could envisage. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「existential graph」の詳細全文を読む スポンサード リンク
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