The mosaic classes of the human genome. Each circle represents one of the mosaic classes. The position of the circle shows the A/C/G/T content:-(a) T+C by A+T, (b) T+G by A+T, (c) T+G by T+C. The area of the circle shows the proportion of the genome contained in the class. The preferred classes (pairs 2, 7, 9 and 14) contain the most transcription factor binding sites and are shown in red. The classes of pair 6 are comparatively long: they are plotted in the same way as the others but are shown in blue. The purpose of this plot is to give a visualisation of the mosaic classes. The genome is AT rich so it is not surprising that there is a preponderance of classes on the right hand side of Figures 1A and 1B. Strand symmetry gives an exact symmetry about the horizontal line T+C = 0.5 in (a) and T+G = 0.5 in (b). In (c), the strand symmetry shows itself as an axial symmetry--that is the line between paired classes is bisected by the central point. All proportions have been calculated from the steady state of the HMM.