The limitations of backpropagation learning can now be overcome by using multilayer neural networks that contain top-down connections and training them to /generate/ sensory data rather than to classify it. (...) much better than previous approaches
In computer science, a kd-tree (short for k-dimensional tree) is a space-partitioning data structure for organizing points in a k-dimensional space. kd-trees are a useful data structure for several applications, such as searches involving a multidimensional search key (e.g. range searches and nearest neighbour searches).
T. Rezende, and S. Almeida. Workshop of Theses and Dissertations (WTD) in the 29th Conference on Graphics, Patterns and Images (SIBGRAPI'16), São José dos Campos, SP, Brazil, Universidade Federal de São Paulo (UniFeSP), (2016)