How to Construct Deep Recurrent Neural Networks
This work addresses the challenge of extending RNNs to deeper architectures for improved performance in sequence modeling tasks like music and language, representing an incremental advancement over prior stacking methods.
The paper tackles the problem of constructing deep recurrent neural networks (RNNs) by identifying three points for depth and proposing two novel architectures, showing that these deep RNNs outperform shallow RNNs on polyphonic music prediction and language modeling tasks.
In this paper, we explore different ways to extend a recurrent neural network (RNN) to a \textit{deep} RNN. We start by arguing that the concept of depth in an RNN is not as clear as it is in feedforward neural networks. By carefully analyzing and understanding the architecture of an RNN, however, we find three points of an RNN which may be made deeper; (1) input-to-hidden function, (2) hidden-to-hidden transition and (3) hidden-to-output function. Based on this observation, we propose two novel architectures of a deep RNN which are orthogonal to an earlier attempt of stacking multiple recurrent layers to build a deep RNN (Schmidhuber, 1992; El Hihi and Bengio, 1996). We provide an alternative interpretation of these deep RNNs using a novel framework based on neural operators. The proposed deep RNNs are empirically evaluated on the tasks of polyphonic music prediction and language modeling. The experimental result supports our claim that the proposed deep RNNs benefit from the depth and outperform the conventional, shallow RNNs.