Bonnet saw that tree branches and leaves had a mathematical spiral pattern that could be shown as a fraction.
Bonnet认识到树枝和树叶具有一种螺旋布局模式，在数学上可以用分数来表达。
2
Generally, model can be expressed by classification rule, decision tree and mathematical formula.
通常，模型可以用分类规则、判定树或数学公式表示。
3
Accident tree analysis is applied to risk analysis and a mathematical model is established, including fire model, effective release rate model, heat intensity threshold and hazard area equation.