Use the + and − buttons to add and remove operands. Operands without a transform will pick one at random.
The transformation
It can be represented as a matrix:
With the arrow indicating the direction of the transformation (substituting × for the original + marks to avoid confusion).
This can be read as the adjacency matrix of a directed graph, where every node has exactly one outbound edge. Ashby says,
If the graph consisted of buttons (the operands) tied together with string (the transitions) it could, as a network, be pulled into different shapes: