Until the middle of the 20th century, musical notation has been detailed as much as possible while there was a tendency to give more importance to the composer’s control over the work; since the second half of the 20th century, the performer has been more involved in the compositional process, taking initiative in various ways during the performance. In addition to the works that have been completely or partially left open to the decisions of the performer thus exhibit a completely new experience in each performance; there are also some other works in which the composers deliberately keep themselves out of the compositional process but the musical result would be more or less the same. Consequently, new concepts such as indeterminacy, aleatory and chance music have taken place in the music literature.


Keywords: Indeterminacy, aleatory, chance, graphic notation, modern music, open work