What does 即 mean in ...Google在ICML文中描述的非常清晰，即在每次SGD时...? According to the top answer over 知乎 on the question 深度学习中 Batch Normalization为什么效果好？:


  顾名思义，batch normalization嘛，就是“批规范化”咯。Google在ICML文中描述的非常清晰，即在每次SGD时，通过mini-batch来对相应的activation做规范化操作，使得结果（输出信号各个维度）的均值为0，方差为1.


What does the 即 mean? Does this function as be? In this case, is it necessary to use 即, instead of 在每次SGD时, and also why is 即 preferred to other words that mean be, such as 是，为, etc...?
即 itself can mean "equal".  For example: '五人即一伍' (Five men equal one unit)

~ you can replace 即 (equal) with 為(be), For example:  '五人為一伍' (Five men is one unit)

But 即 can be short for 即是 (namely; that is to say; to be specific)

Example:

[1. 軍隊將士兵分伍] [2. 即] [3.每五人組成一個單位]

[1. Amy divides soldiers into 伍] [2. to be specific ] [3. Every five people become one unit]

[1. general statement] [2. to be specific] [3. detail description]