Methods and apparatus for modeling formations are disclosed. The steering mechanism includes a pair of drive gears interlocking with the steering operation device and a pair of follower gears interlocking with the respective steerable running wheels. V represents O, S, N, C, P, or Si, and W is an anion. Additionally, each wall is provided with a doorway, with the doorways of each wall being aligned with each other. Both the phases and frequencies of the individual clocks over time are estimated.