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Abstract

With the emergence of big data, inducting regression trees on very large data sets became a common data mining task. Even though centralized algorithms for computing ensembles of Classification/Regression trees are a well studied machine learning/data mining problem, their distributed versions still raise scalability, efficiency and accuracy issues. Most state of the art tree learning algorithms require data to reside in memory on a single machine. Adopting this approach for trees on big data is not feasible as the limited resources provided by only one machine lead to scalability problems. While more scalable implementations of tree learning algorithms have been proposed, they typically require specialized parallel computing architectures rendering those algorithms complex and error-prone. In this thesis we will introduce two approaches to computing ensembles of regression trees on very large training data sets using the MapReduce framework as an underlying tool. The first approach employs the entire MapReduce cluster to parallely and fully distributedly learn tree ensembles. The second approach exploits locality and independence in the tree learning process.