A: Mitte, Halle (Saale), Sachsen-Anhalt, Germany

1879

In 1879 Friedrich Ludwig Gottlob Frege published in Halle, Germany his *Begriffsschrift, eine der arithmetischen nachgebildete Formelsprache des reinen Denkens*.

“. . . although a mere booklet of eighty-eight pages, it is perhaps the most important single work ever written in logic. Its fundamental contributions, among lesser points, are the truth-functional propositional calculus, the analysis of the proposition into function and argument(s) instead of subject and predicate, the theory of quantification, a system of logic in which derivations are carried out exclusively according to the form of the expressions, and a logical definition of the notion of mathematical sequence. Any single one of these achievements would suffice to secure the book a permanent place in the logician’s library” (Van Heijenoort, *From Frege to Gödel* (1967) 1).

“In his attempt to give a satisfactory definition of number and a rigorous foundation to arithmetic, Frege found ordinary language insufficient. To overcome the difficulties involved, he devised his *Begriffschrift* as a tool for analyzing and representing mathematical proofs completely and adequately. This tool has gradually developed into modern mathematical logic, of which Frege may justly be considered the creator“ (*Dictionary of Scientific Biography* article on Frege).