Fig 2.3. The forest from Fig. 2.1. Shown to the right of each vertex are its j-number (above) and its working label (below). A working label consists of the i-number of the vertex followed by the j-number of its parent. The working label for a root is its i-number. The seven blocks of the automorphism partition are shown below the forest. These are found by making all vertices which have the same depth and.j-number equivalent.