Kraanerg

Kraanerg is a composition for 23 instruments and 4-channel analog tape composed by Iannis Xenakis, originally for a ballet with choreography by Roland Petit and set design by Victor Vasarely. It was created for the grand opening of the Canadian National Arts Centre in Ottawa, which was originally to coincide with Expo 67 but was delayed to 1969.
The title, by Xenakis, is an imaginary compound of the Greek-originating stems "kraan" (κρααν) and "erg" (εργ), meaning "accomplished action". According to the composer's program notes, the title also refers to the "current youth movements" of that time, and his vision of the imminent "biological struggle between generations unfurling all over the planet, destroying existing political, social, urban, scientific, artistic, and ideological frameworks on a scale never before attempted by humanity." The program was left up to Xenakis, and he chose to avoid any narrative or story; the abstract modernistic character of the ballet was to be underscored by Vasarely's Op Art set design. Xenakis had previously written the soundtrack for a 1960 film about Vasarely.
The 75-minute piece is not divided into movements but includes twenty periods of silence of varying length (three of them more than twenty seconds) which are integral to the development. It has three phases of roughly equal duration: the first contains more or less equal portions of both orchestra and tape; the second (beginning after 23 minutes), primarily instruments; and the third (beginning after 52 minutes) primarily tape. The sounds on the tape are derived from instrumental material. The choreography by Petit (who was in charge of the premiere, and divided the work at its midpoint with an intermission) was a critical failure, but the music was widely praised; it was conducted at the premiere by Lukas Foss, who like Vasarely was invited to the project by Xenakis. After a tour of the original ballet that ended in 1972, "Kraanerg" was largely forgotten for some years. It was revived in 1988 with a new choreography by Australian choreographer Graeme Murphy, a performance which was regarded as much more successful than the original one. However, subsequently the music has usually been performed without the ballet.
Discography.
In chronological order.