TP1-valid Transformation Functions for Operations on ordered n-ary Trees

Collaborative work on shared documents was revolutionized by web services like Google Docs or Etherpad. Multiple users can work on the same document in a comfortable and distributed way. For the synchronization of the changes a replication system named Operational Transformation is used. Such a system consists of a control algorithm and a transformation function. In essence, a transformation function solves the conflicts that arise when multiple users change the document at the same time. In this work we investigate on the correctness of such transformation functions. We introduce transformation functions n-ary trees that we designed especially for the purpose of synchronization changes on JSON objects. We provide a detailed proof of the necessary property: the Transformation Property 1.