Conversation so far:
Was John Cage's style of composition different than composers before him?
John Cage's work from the sixties features some of his largest and most ambitious, not to mention socially utopian pieces, reflecting the mood of the era.
In what way were John Cage's work from the sixties ambitious?
HPSCHD (1969) was a gargantuan and long-running multimedia work John Cage made in collaboration with Lejaren Hiller.

Question: What was the rhythmic structure of these pieces?
Self-contained rewrite: What was the rhythmic structure of these pieces?