1. A method comprising: transforming between one or more electrical digital signals representing a tree and one or more electrical digital signals representing a condensed array of numerals by: (a) identifying a label value associated with a node of said tree; (b) factoring said label value into two or more non-composite factors; (c) associating said non-composite factors with indices of said condensed array of numerals, wherein said condensed array comprises a fixed number of rows or a fixed number of columns; (d) determining numerals representing one or more descendent nodes directly connected to said node based, at least in part, on said indices; and (e) recursively applying (a) through (d) to said descendent nodes to determine numerals representing remaining nodes descendent from said node, wherein each frontier node of said tree is associated with a label value comprising a non-composite numeral times an integer number of terminal nodes descending from said frontier node.