Page 2 of "[Is 'the theory of everything' merely the ultimate ensemble theory?][1]" by Max Tegmark contains the following image: ![Relationships between various basic mathematical structures][2] [1]: http://arxiv.org/abs/gr-qc/9704009 [2]: http://24.media.tumblr.com/tumblr_lil7n0uiEl1qfjvexo1_500.png