Rudas Anna (BME) "Entropy and Hausdorff dimension in random growing trees"

We investigate the limiting behaviour of random tree growth in preferential attachment models. The tree stems from a root, and we add vertices to the system one-by-one at random, according to a rule which depends on the degree distribution of the already existing tree. The so-called weight function, in terms of which the rule of attachment is formulated, is such that each vertex in the tree can have at most K children. We define the concept of a certain random measure $\mu$ on the leaves of the limiting tree, which captures a global property of the tree growth in a natural way. We prove that the Hausdorff and the packing dimension of this limiting measure is equal and constant with probability one. Moreover, the local dimension of $\mu$ equals the Hausdorff dimension at $\mu$-almost every point. We give an explicit formula for the dimension, given the rule of attachment.