Gottlob Frege's predicate logic builds upon propositional logic, and has been described as combining "the distinctive features of syllogistic logic and propositional logic." Consequently, predicate logic ushered in a new era in logic's history; however, advances in propositional logic were still made after Frege, including natural deduction, truth trees and truth tables. Natural deduction was invented by Gerhard Gentzen and Stanisław Jaśkowski. Truth trees were invented by Evert Willem Beth.Beth, Evert W.; "Semantic entailment and formal derivability", series: Mededlingen van de Koninklijke Nederlandse Akademie van Wetenschappen, Afdeling Letterkunde, Nieuwe Reeks, vol. 18, no. 13, Noord-Hollandsche Uitg. Mij., Amsterdam, 1955, pp. 309–42. Reprinted in Jaakko Intikka (ed.) The Philosophy of Mathematics, Oxford University Press, 1969 The invention of truth tables, however, is of uncertain attribution.
gottlob frege's predicate logic builds upon propositional logic and has been described as combining "the distinctive features of syllogistic logic and propositional logic" consequently predicate logic ushered in a new era in logic's history; however advances in propositional logic were still made after frege including natural deduction truth trees and truth tables natural deduction was invented by gerhard gentzen and stanisław jaśkowski truth trees were invented by evert willem bethbeth evert w; "semantic entailment and formal derivability" series mededlingen van de koninklijke nederlandse akademie van wetenschappen afdeling letterkunde nieuwe reeks vol 18 no 13 noord-hollandsche uitg mij amsterdam 1955 pp 309–42 reprinted in jaakko intikka (ed) the philosophy of mathematics oxford university press 1969 the invention of truth tables however is of uncertain attribution