invariant of order P P

例句：

1. 1.The invariant is a constant value that remains unchanged over time.
   不变式是一个在时间上保持不变的常数值。
2. 2. The invariant equation describes the relationship between two variables.
   不变式方程描述了两个变量之间的关系。
3. 3. The invariant of order P P is the only solution to the differential equation.
   P阶的不变式是微分方程的唯一解。