Here λ is a hyper-parameter that balances the weights of the neural network model and the language model.
the state d c n for step n in the characterlevel decoder is defined as follows, where GRU c dec are parameters for the gated recurrent cell of this decoder: if the corresponding token in the source x zs is also an out-of-vocabulary word, we define a second nested level of character attention and use it in the character-level decoder.