程序之交換律 Commutative Property of Process

程序，其步驟順序交換而發生同一結果者，合於交換律。	A process is commutative if we can derive the same result after we change the orders of the steps of the process.
不合於交換律之程序，其步驟順序交換而疑似發生同一結果者，蓋隱含另一結果未經察覺。	Where we seems to derive the same result after we change the orders of the steps of a non-commutative process, there is actually another implicit result remaining unobserved.