Evryali (from Ancient Greek: Εὐρυάλη Euryale) is a piece for solo piano composed by Iannis Xenakis in 1973.
It is based on a technique Xenakis invented in early 1970s, called arborescences—proliferations of melodic lines created from a generative contour.
On the most basic level, one can distinguish five of these: fixed rhythmic passages, stochastic clouds, polyphonic arborescences, monophonic waves and silence.
A more complex analysis, offered by musicologist Ronald Squibbs, reveals that Evryali has four distinct "configuration types".
[7] According to this classification, there are fifty segments overall in Evryali: 23 for time-point sequences, 4 for stochastic material (appearing only at two points in the work, both times as consecutive pairs), 20 for arborescences, and 3 are silences.