why use predictor NET P as training objective ,not use IC ,ICIR directly?

[silentsky2billten]

why use predictor NET P as training objective ,not use IC ,ICIR directly?
is there any benefit?

[DulyHao]

That is the core problem that we are going to solv. IC is not directly differentiable to the Generator, it could not be cauculated mathmatically from the onehot encoding of a factor expression.