A mature design result is not casual and random, but coming from a gradual design process. Beginning with a simple form, the product transforms step-by-step to cumulate the final form.
The author uses the distribution of pebbles to illustrate the system with randomness. and he introduces the concept of sieve. This non-randomness distribution of pebbles principle is known as the sieve device. Also, he make a distinction between “single-step” selection and ” cumulative” selection.
Introduce a simple-drawing rule for computer to obey easily. Use tree-growing procedure to draw a single line, and then branches split into two. Becomes “recursive”.
The criterion of computer section is different from natural selection. The key point to selection is based on the ability to appeal to human whim.
It shows how the bruches changes gradually by a main line of evolution.
The author starts with biology and uses genes as examples to demonstrate the process of biological creation, and then transforms into a method of introducing computer modeling. Although it is not the same as the knowledge in biology, it can also effectively help us to think about how to make model through the inspiration getting from biology.