A Deep Multi-task Model for Dialogue Act Classification, Intent Detection and Slot Filling

An essential component of any dialogue system is understanding the language which is known as spoken language understanding (SLU). Dialogue act classification (DAC), intent detection (ID) and slot filling (SF) are significant aspects of every dialogue system. In this paper, we propose a deep learning-based multi-task model that can perform DAC, ID and SF tasks together. We use a deep bi-directional recurrent neural network (RNN) with long short-term memory (LSTM) and gated recurrent unit (GRU) as the frameworks in our multi-task model. We use attention on the LSTM/GRU output for DAC and ID. The attention outputs are fed to individual task-specific dense layers for DAC and ID. The output of LSTM/GRU is fed to softmax layer for slot filling as well. Experiments on three datasets, i.e. ATIS, TRAINS and FRAMES, show that our proposed multi-task model performs better than the individual models as well as all the pipeline models. The experimental results prove that our attention-based multi-task model outperforms the state-of-the-art approaches for the SLU tasks. For DAC, in relation to the individual model, we achieve an improvement of more than 2% for all the datasets. Similarly, for ID, we get an improvement of 1% on the ATIS dataset, while for TRAINS and FRAMES dataset, there is a significant improvement of more than 3% compared to individual models. We also get a 0.8% enhancement for ATIS and a 4% enhancement for TRAINS and FRAMES dataset for SF with respect to individual models. Results obtained clearly show that our approach is better than existing methods. The validation of the obtained results is also demonstrated using statistical significance t tests.