Iannis Xenakis (May 29, 1922 – February 4, 2001) was a Greek composer, music theorist and architect. He is commonly recognized as one of the most important post-war avant-garde composers. Xenakis pioneered the use of mathematical models such as applications of set theory, varied use of stochastic processes, game theory, etc., in music, and was also an important influence on the development of electronic music.
I've just heard a piece by Xenakis for string orchestra called Shaar, live in concert. The textures were rich, the sonorities amazing as he really pushed the instruments to their limit.
I haven't heard anything else by him, so I would be interested in the views and information about good recordings, etc. by people who are more familiar with him...