Fragmentation of Ordered Partitions and Intervals

Abstract

Fragmentation processes of exchangeable partitions have already been studied by several authors. This paper deals with fragmentations of exchangeable compositions, i.e. partitions of $\mathbb{N}$ in which the order of the blocks matters. We will prove that such a fragmentation is bijectively associated to an interval fragmentation. Using this correspondence, we then study two examples: Ruelle's interval fragmentation and the interval fragmentation derived from the standard additive coalescent.