"Grundgesetze" he revises slightly his interpretation of the ├─ symbol. In "Begriffsschrift" the "Definitionsdoppelstrich" (i.e. definition double stroke) │├─ indicates that a proposition is a definition. Furthermore, the negation sign can be read as a combination of the horizontal Inhaltsstrich with a vertical negation stroke. This negation symbol was reintroduced by Arend Heyting in 1930 to distinguish intuitionistic from classical negation. It also appears in Gerhard Gentzen's doctoral dissertation. In the Tractatus Logico Philosophicus, Ludwig Wittgenstein pays homage to Frege by employing the term Begriffsschrift as a synonym for logical formalism. Frege's 1892 essay, "On Sense and Reference," recants some of the conclusions of the Begriffsschrifft about identity (denoted in mathematics by the "=" sign). In particular, he rejects the "Begriffsschrift" view that the identity predicate expresses a relationship between names, in favor of the conclusion that it expresses a relationship between the objects that are denoted by those names. Editions Gottlob Frege. Begriffsschrift: eine der arithmetischen nachgebildete Formelsprache des reinen Denkens. Halle an der Saale: Verlag von Louis Nebert, 1879. Translations: Bynum, Terrell Ward, translated and edited, 1972. Conceptual notation and related articles, with a biography and introduction. Oxford University Press. Bauer-Mengelberg, Stefan, 1967, "Concept Script" in Jean van Heijenoort, ed., From Frege to Gödel: A Source Book in Mathematical Logic, 1879–1931. Harvard University Press. Beaney, Michael, 1997, "Begriffsschrift: Selections (Preface and Part I)" in The Frege Reader. Oxford: Blackwell. See also Ancestral relation Calculus of equivalent statements First-order logic Frege's propositional calculus Prior Analytics The Laws of Thought Principia Mathematica References Bibliography George Boolos, 1985. "Reading the Begriffsschrift", Mind 94: 331–344. Ivor Grattan-Guinness, 2000. In Search of Mathematical Roots. Princeton University Press. Risto Vilkko, 1998, "The reception of Frege's Begriffsschrift," Historia Mathematica 25(4): 412–422. External links Begriffsschrift as facsimile for download (2.5 MB) Esoteric programming language: 1879 non-fiction books Books by Gottlob Frege Logic books Diagram algebras Analytic philosophy literature Philosophy of logic Classical logic Predicate logic