An attempt to categorise the vast field of pure and applied mathematics would perhaps seem too pedantic at first sight. It is the nature of the thing that gives the pleasure and its categorisation isn't a prerequisite to its understanding. However, there are many advantages arising from such an 'administrative' effort, perhaps the most important of which is the mere feeling that the forest ahead seems less foggy to the mind's eye, since one knows where the main paths lay ahead. A sense of orientation is thus cultivated in the pursuit of knowledge in mathematics, both in the mastery of technique and in the understanding of sophisticated notions. In this spirit I wondered today whether a chart of the categories, divisions of these categories (and subdivisions of these.. ad infinitum?) exists. An all encompassing diagram. Even a smaller per category would do but why not be adventurous and optimistic at first. Such a diagram would show the links between the fields and branches of mathematics thus making it quite a different thing from a list of categories. I didn't find a sufficiently thorough one online and so I'd like to ask everyone in this forum whether they have seen such a poster with arrows connecting the subjects showing the origin(s) of each branch from the more fundamental to the more specific ones. What I did find, and would like to share with you, is a thorough list of subjects (about 100) and a picture relating those subjects but in a slightly different way than a diagram does (causal or historical relation is absent). This is the scheme developed by the American Mathematical Society and Zentralblatt für Mathematik: www.math-atlas.org (and http://www.math.niu.edu/~rusin/known-math/index/index.html) Surely this would be enough information to create such a diagram. A suggestion to the moderators of this great forum.