Loss of A2C algorithm

[yingchengyang]

I'd like to ask about the loss of a2c algorithm. There are three part of loss in tianshou's code:
loss = a_loss + self._w_vf * vf_loss - self._w_ent * ent_loss
I'd like to ask about the meaning of the third part of the loss. I try use this to run in CartPole-v0, it converge after 1355 steps,then I try use only the first and second part of loss to run in CartPole-v0, it converge after 770 steps. It seems that only use the first and second part of loss is enough?

[Trinkle23897]

The third loss is about the policy entropy loss. In other repo such as openai baseline, their A2C/A3C implementation has this term, so I add the entropy loss here.
Of course you can set the weight of entropy loss to zero :)

[yingchengyang]

thanks！