title: Does Keras Adam Optimizer and other momemtum-based optimizers retain its past update information over different fit calls?
body: <p>The Adam optimizer uses a momentum-like approach to train a neural network in fewer iterations of gradient descent than vanilla gradient descent. I'm trying to figure out whether the Adam optimizer works in a Q-learning situation where you have a non-stationary dataset and numerous model.fit() calls. Does Adam and other optimizers retain their momentum over the different calls or is the state of the optimizer reset at each fit call?
  I've tried searching the code on <a href="https://github.com/keras-team/keras/blob/master/keras/optimizers.py#L436" rel="nofollow noreferrer">https://github.com/keras-team/keras/blob/master/keras/optimizers.py#L436</a> but can't find where this information is stored and whether it's retained.</p>