Program notes software news

For reasons that may say something about computer science as a discipline, the trees that programmers build have their roots at the top and their branches at the bottom. This lets readers scan from a top-level entry to more detailed subparts, but it may confuse those used to the natural kind of tree. Trees are best used to store data that is hierarchically organized; their structure corresponds to the natural structure of such data, and the distance from the root to any leaf is much smaller than the length of a linear list containing the same data.