Iannis Xenakis (Greek: Γιάννης (Ιάννης) Ξενάκης ; 29 May 1922 – 4 February 2001) was a Greek-French composer, music theorist, and architect-engineer. After 1947, he fled Greece, becoming a naturalized citizen of France. He is commonly recognized as one of the most important post-war avant-garde composers. Xenakis pioneered the use of mathematical models in music such as applications of set theory, stochastic processes and game theory and was also an important influence on the development of electronic and computer music. He integrated music with architecture, designing music for pre-existing spaces, and designing spaces to be integrated with specific music compositions and performances.