Below is the same structure in graphical representation (the opposition normal boxes/shaded boxes is used to distinguish a class from an indexed element, respectively). It should be noted that the value more general/more specific is apt to vary for the same classes. For example, in this case, one could easily invert the structure and set up //plant// and //animal// as encompassing classes, and //inedible// and //edible// as encompassed classes (so that each encompassing class would have an //inedible// class and an //edible// class under it).
In this section the emergence and development of modern computer-based classification is presented first, partly as a new field of mathematics but also as methodological research in ecology. The references included in the first subsection ( Clustering and Classification ) strictly concern clustering and classification. These, however, are rarely used in isolation but instead are combined with other methods of multivariate analysis. One is ordination, a group of methods aimed at presenting the resemblance structure of populations graphically. As such, it is a means to illustrate the outcome of classification. The books mentioned in the second subsection ( Numerical Ecology ) all include this and even more topics related to ecological research.