Editing Mathematical logic (section)

====Beginnings of the other branches====
[[Alfred Tarski]] developed the basics of [[model theory]].

Beginning in 1935, a group of prominent mathematicians collaborated under the pseudonym [[Nicolas Bourbaki]] to publish ''[[Éléments de mathématique]]'', a series of encyclopedic mathematics texts. These texts, written in an austere and axiomatic style, emphasized rigorous presentation and set-theoretic foundations. Terminology coined by these texts, such as the words [[bijection, injection, and surjection|''bijection'', ''injection'', and ''surjection'']], and the set-theoretic foundations the texts employed, were widely adopted throughout mathematics.

The study of computability came to be known as recursion theory or [[computability theory]], because early formalizations by Gödel and Kleene relied on recursive definitions of functions.{{efn|A detailed study of this terminology is given by {{harvnb|Soare|1996}}.}} When these definitions were shown equivalent to Turing's formalization involving [[Turing machine]]s, it became clear that a new concept &ndash; the [[computable function]] &ndash; had been discovered, and that this definition was robust enough to admit numerous independent characterizations. In his work on the incompleteness theorems in 1931, Gödel lacked a rigorous concept of an effective formal system; he immediately realized that the new definitions of computability could be used for this purpose, allowing him to state the incompleteness theorems in generality that could only be implied in the original paper.

Numerous results in recursion theory were obtained in the 1940s by [[Stephen Cole Kleene]] and [[Emil Leon Post]]. Kleene{{sfnp|Kleene|1943}} introduced the concepts of relative computability, foreshadowed by Turing,{{sfnp|Turing|1939}} and the [[arithmetical hierarchy]]. Kleene later generalized recursion theory to higher-order functionals. Kleene and [[Georg Kreisel]] studied formal versions of intuitionistic mathematics, particularly in the context of proof theory.
<!-- Perhaps it is better to stop this history around 1950 -->