Another attribute 'rankdir' controls the direction the nodes are linked together. The 'width' and 'height' attributes control the size of the bounding box of the drawing in inches. The default is not to merge edges. The default is not random. For undirected graphs, the 'epsilon' attribute decides how long the graph solver tries before finding a graph layout.
Lower numbers allow the solver to fun longer and potentially give a better layout.
Larger values can decrease the running time but with a reduction in layout quality. The default is 0.1. The value should be a hash reference containing the corresponding key-value pairs. All nodes have a name attached which uniquely represents that node. If not specified, the 'fillcolor' when the 'style' is 'filled' defaults to be the same as the outline color style sets the style of the node.