Taxonomy (biology) new common (or apomorphic) traits. However, certain phenetic methods, such as neighbor joining, have found their way into cladistics, as a reasonable approximation of phylogeny when more advanced methods (such as Bayesian inference) are too computationally expensive. Modern taxonomy uses database technologies to search and catalogue classifications and their documentation. While there is no commonly used database, there are comprehensive databases such as the "Catalogue of Life", which attempts to list every documented species. The catalogue listed 1.64 million species for all kingdoms as of April 2016, claiming coverage of more than three quarters of the estimated species known to
Structure (category theory) operations will be needed. "Presentation of a category" (analogously to presentation of a group) can in fact be approached in a number of ways, the "category" structure not being (quite) an algebraic structure in its own right. The term "transport of structure" is the 'French' way of expressing "covariance" or "equivariance" as a constraint: transfer structure by a surjection and then (if there is an existing structure) compare. Since any group is a one-object category, a special case of the question about "what the morphisms preserve" is this: how to consider any group G as a symmetry group? That is