Is reward_fn equal to log_softmax

[EganGu]

I noticed that the scores in reward_fn is actually equal to logits_i - logsumexp(logits). I think this expression can be calculated directly by log_softmax. Why not use log_softmax?

https://github.com/microsoft/LMOps/blob/5fbf5bcd6e6760fa95aaaf945fb5d9cb033135f6/minillm/minillm/reward.py#L33