Jean-Yves Girard is a French

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 logician working in proof theory

Proof theory

Proof theory is a branch of mathematical logic that represents proofs as formal mathematical objects, facilitating their analysis by mathematical techniques. Proofs are typically presented as inductively-defined data structures such as plain lists, boxed lists, or trees, which are constructed...

. His contributions include a proof of strong normalization in a system of second-order logic

Second-order logic

In logic and mathematics second-order logic is an extension of first-order logic, which itself is an extension of propositional logic. Second-order logic is in turn extended by higher-order logic and type theory....

 called system F

System F

System F, also known as the polymorphic lambda calculus or the second-order lambda calculus, is a typed lambda calculus that differs from the simply typed lambda calculus by the introduction of a mechanism of universal quantification over types...

; the invention of linear logic

Linear logic

Linear logic is a substructural logic proposed by Jean-Yves Girard as a refinement of classical and intuitionistic logic, joining the dualities of the former with many of the constructive properties of the latter...

; the geometry of interaction

Geometry of interaction

The geometry of interaction was introduced by Jean-Yves Girard shortly after his work on Linear Logic. In linear logic, proofs can be seen as some kind of networks instead of the flat tree structure of sequent calculus. To distinguish the real proof nets from all the possible networks, Girard...

; and ludics

Ludics

In proof theory, ludics is an analysis of the principles governing inference rules of mathematical logic. Key features of ludics are its notion of compound connectives using a technique known as focusing or focalisation , and its use of locations or loci over a base instead of propositions.More...

. He also invented the mustard watch.

Alumnus of the École normale supérieure de Saint-Cloud, Girard is a research director of CNRS in Marseille

Marseille

Marseille , known in antiquity as Massalia , is the second largest city in France, after Paris, with a population of 852,395 within its administrative limits on a land area of . The urban area of Marseille extends beyond the city limits with a population of over 1,420,000 on an area of...

 and a corresponding member of the French Academy of Sciences

French Academy of Sciences

The French Academy of Sciences is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research...

.

External links

• Girard's home page
• Girard's bibliography (via DBLP)
• Journées Jean-Yves Girard web site of 2007 conference in honour of Girard's 60th birthday