Very simple mathematical expressions are mapped onto the automatic piano (see picture), which can play all keys at the same time, fast repetitions etc.
frühling: consinsts of falling scales
sommer1: all keys of the piano are played at the same time, but each key with a different rhythm, which is a multiple of a prime number. So there are never two keys playing at exactly the same time.
sommer2: like sommer1, but now the lowest key has the slowest rhythm
winter: is a constantly "growing" cluster from one key to all 88 keys in a nearly constant rhythm. Afterwards the keys are released in the inverse order.
The algorithms are realized within the open source software PD.