  Tree ensemble algorithms as RandomForest and GradientBoosting are currently
the dominant methods for modeling discrete or tabular data, however, they are
unable to perform a hierarchical representation learning from raw data as
NeuralNetworks does thanks to its multi-layered structure, which is a key
feature for DeepLearning problems and modeling unstructured data. This
limitation is due to the fact that tree algorithms can not be trained with
back-propagation because of their mathematical nature. However, in this work,
we demonstrate that the mathematical formulation of bagging and boosting can be
combined together to define a graph-structured-tree-ensemble algorithm with a
distributed representation learning process between trees naturally (without
using back-propagation). We call this novel approach Distributed Gradient
Boosting Forest (DGBF) and we demonstrate that both RandomForest and
GradientBoosting can be expressed as particular graph architectures of DGBT.
Finally, we see that the distributed learning outperforms both RandomForest and
GradientBoosting in 7 out of 9 datasets.
