When Xenakis creates compositional implementations of theoretical models, he frequently “intervenes” and introduces many “discrepancies”. All Xenakis specialists, when comparing the theoretical models with the scores, have noted that there are important “gaps” between the data predicted by the former and the data found in the latter. In other words, the implementations are not mechanical, but are mediated through manual interventions. Sometimes, these interventions affect not only the musical implementation of the formal system (the theoretical model), but also its construction