• Basic models for slot filling and intent detection:
  • An implementation for "focus" part of the paper "Encoder-decoder with focus-mechanism for sequence labelling based spoken language understanding".
  • An implementation of BLSTM-CRF based on jiesutd/NCRFpp
  • An implementation of joint training of slot filling and intent detection tasks (Bing Liu and Ian Lane, 2016).
• Basic models + ELMo / BERT / XLNET
• Tutorials on ATIS, SNIPS and MIT_Restaurant_Movie_corpus(w/o intent) datasets.

• python 3.6.x
• pytorch 1.1
• pip install gpustat [if gpu is used]
• ELMo in allennlp: pip install allennlp
• BERT/XLNET in pytorch-transformers: pip install pytorch-transformers

As we can know from the datasets, ATIS may have multiple intents for one utterance while SNIPS has only one intent for one utterance. For example, "show me all flights and fares from denver to san francisco <=> atis_flight && atis_airfare". Therefore, there is a public trick in the training and evaluation stages for intent detection of ATIS dataset.

NOTE: Impacted by the paper "What is left to be understood in ATIS?", almost all works about ATIS choose the first intent as the label to train a "softmax" intent classifier. In the evaluation stage, it will be viewed as correct if the predicted intent is one of the multiple intents.

• Add char-embeddings

1. Pretrained word embeddings are borrowed from CNN-BLSTM language models of ELMo where word embeddings are modelled by char-CNNs. We extract the pretrained word embeddings for ATIS, SNIPS and MIT_Restaurant_Movie_corpus(w/o intent) datasets by:

  python3 scripts/get_ELMo_word_embedding_for_a_dataset.py \
          --in_files data/atis-2/{train,valid,test} \
          --output_word2vec local/word_embeddings/elmo_1024_cased_for_atis.txt
  python3 scripts/get_ELMo_word_embedding_for_a_dataset.py \
          --in_files data/snips/{train,valid,test} \
          --output_word2vec local/word_embeddings/elmo_1024_cased_for_snips.txt
  python3 scripts/get_ELMo_word_embedding_for_a_dataset.py \
          --in_files data/MIT_corpus/{movie_eng,movie_trivia10k13,restaurant}/{train,valid,test} \
          --output_word2vec local/word_embeddings/elmo_1024_cased_for_MIT_corpus.txt

2. Run scripts of training and evaluation at each epoch.

• BLSTM model:

bash run/atis_with_pretrained_word_embeddings.sh slot_tagger
bash run/snips_with_pretrained_word_embeddings.sh slot_tagger
bash run/MIT_corpus_with_pretrained_word_embeddings.sh slot_tagger

• BLSTM-CRF model:

bash run/atis_with_pretrained_word_embeddings.sh slot_tagger_with_crf
bash run/snips_with_pretrained_word_embeddings.sh slot_tagger_with_crf
bash run/MIT_corpus_with_pretrained_word_embeddings.sh slot_tagger_with_crf

• Enc-dec focus model (BLSTM-LSTM), the same as Encoder-Decoder NN (with aligned inputs)(Liu and Lane, 2016):

bash run/atis_with_pretrained_word_embeddings.sh slot_tagger_with_focus
bash run/snips_with_pretrained_word_embeddings.sh slot_tagger_with_focus
bash run/MIT_corpus_with_pretrained_word_embeddings.sh slot_tagger_with_focus

1. Run scripts of training and evaluation at each epoch.

• ELMo + BLSTM/BLSTM-CRF/Enc-dec focus model (BLSTM-LSTM) models:

slot_intent_model=slot_tagger # slot_tagger, slot_tagger_with_crf, slot_tagger_with_focus
bash run/atis_with_elmo.sh ${slot_intent_model}
bash run/snips_with_elmo.sh ${slot_intent_model}
bash run/MIT_corpus_with_elmo.sh ${slot_intent_model}

0. Model architectures:

• Joint BERT or "with pure BERT":

• Our BERT + BLSTM (BLSTM-CRF\Enc-dec focus):

1. Run scripts of training and evaluation at each epoch.

• Pure BERT (without or with crf) model:

slot_model=NN # NN, NN_crf
intent_input=CLS # none, CLS, max, CLS_max
bash run/atis_with_pure_bert.sh ${slot_model} ${intent_input}
bash run/snips_with_pure_bert.sh ${slot_model} ${intent_input}
bash run/MIT_corpus_with_pure_bert.sh ${slot_model} ${intent_input}

• BERT + BLSTM/BLSTM-CRF/Enc-dec focus model (BLSTM-LSTM) models:

slot_intent_model=slot_tagger # slot_tagger, slot_tagger_with_crf, slot_tagger_with_focus
bash run/atis_with_bert.sh ${slot_intent_model}
bash run/snips_with_bert.sh ${slot_intent_model}
bash run/MIT_corpus_with_bert.sh ${slot_intent_model}

2. For optimizer, you can try BertAdam and AdamW. In my experiments, I choose to use BertAdam.

1. Run scripts of training and evaluation at each epoch.

• Pure XLNET (without or with crf) model:

slot_model=NN # NN, NN_crf
intent_input=CLS # none, CLS, max, CLS_max
bash run/atis_with_pure_xlnet.sh ${slot_model} ${intent_input}
bash run/snips_with_pure_xlnet.sh ${slot_model} ${intent_input}
bash run/MIT_corpus_with_pure_xlnet.sh ${slot_model} ${intent_input}

• XLNET + BLSTM/BLSTM-CRF/Enc-dec focus model (BLSTM-LSTM) models:

slot_intent_model=slot_tagger # slot_tagger, slot_tagger_with_crf, slot_tagger_with_focus
bash run/atis_with_xlnet.sh ${slot_intent_model}
bash run/snips_with_xlnet.sh ${slot_intent_model}
bash run/MIT_corpus_with_xlnet.sh ${slot_intent_model}

2. For optimizer, you can try BertAdam and AdamW.

• For "NLU + BERT/XLNET" models, hyper-parameters are not tuned carefully.

1. Results of ATIS:

   models	intent Acc (%)	slot F1-score (%)
   [Atten. enc-dec NN with aligned inputs](Liu and Lane, 2016)	98.43	95.87
   [Atten.-BiRNN](Liu and Lane, 2016)	98.21	95.98
   [Enc-dec focus](Zhu and Yu, 2017)	-	95.79
   [Slot-Gated](Goo et al., 2018)	94.1	95.2
   Intent Gating & self-attention	98.77	96.52
   BLSTM-CRF + ELMo	97.42	95.62
   Joint BERT	97.5	96.1
   Joint BERT + CRF	97.9	96.0
   BLSTM (A. Pre-train word emb.)	98.10	95.67
   BLSTM-CRF (A. Pre-train word emb.)	98.54	95.39
   Enc-dec focus (A. Pre-train word emb.)	98.43	95.78
   BLSTM (B. +ELMo)	98.66	95.52
   BLSTM-CRF (B. +ELMo)	98.32	95.62
   Enc-dec focus (B. +ELMo)	98.66	95.70
   BLSTM (C. +BERT)	99.10	95.94
   BLSTM (D. +XLNET)	98.77	96.08

2. Results of SNIPS:

• Cased BERT-base model gives better result than uncased model.

  models	intent Acc (%)	slot F1-score (%)
  [Slot-Gated](Goo et al., 2018)	97.0	88.8
  BLSTM-CRF + ELMo	99.29	93.90
  Joint BERT	98.6	97.0
  Joint BERT + CRF	98.4	96.7
  BLSTM (A. Pre-train word emb.)	99.14	95.75
  BLSTM-CRF (A. Pre-train word emb.)	99.00	96.92
  Enc-dec focus (A. Pre-train word emb.)	98.71	96.22
  BLSTM (B. +ELMo)	98.71	96.32
  BLSTM-CRF (B. +ELMo)	98.57	96.61
  Enc-dec focus (B. +ELMo)	99.14	96.69
  BLSTM (C. +BERT)	98.86	96.92
  BLSTM-CRF (C. +BERT)	98.86	97.00
  Enc-dec focus (C. +BERT)	98.71	97.17
  BLSTM (D. +XLNET)	98.86	97.05

3. Slot F1-scores of MIT_Restaurant_Movie_corpus(w/o intent):

   models	Restaurant	Movie_eng	Movie_trivia10k13
   Dom-Gen-Adv	74.25	83.03	63.51
   Joint Dom Spec & Gen-Adv	74.47	85.33	65.33
   Data Augmentation via Joint Variational Generation	73.0	82.9	65.7
   BLSTM (A. Pre-train word emb.)	77.54	85.37	67.97
   BLSTM-CRF (A. Pre-train word emb.)	79.77	87.36	71.83
   Enc-dec focus (A. Pre-train word emb.)	78.77	86.68	70.85

• Su Zhu and Kai Yu, "Encoder-decoder with focus-mechanism for sequence labelling based spoken language understanding," in IEEE International Conference on Acoustics, Speech and Signal Processing(ICASSP), 2017, pp. 5675-5679.