## Use Case and High-Level Description¶

This is a BERT-large model pre-trained on lower-cased English text using Whole-Word-Masking and fine-tuned on the SQuAD v1.1 training set. The model performs question answering for English language; the input is a concatenated premise and question for the premise, and the output is the location of the answer to the question inside the premise. For details about the original floating-point model, check out BERT: Pre-training of Deep Bidirectional Transformers for Language Understanding.

Tokenization occurs using the BERT tokenizer (see the demo code for implementation details) and the enclosed vocab.txt dictionary file. Input is to be lower-cased before tokenizing.

The model has been further quantized to INT8 precision using quantization-aware fine-tuning with NNCF.

Metric

Value

GOps

246.93

MParams

333.96

Source framework

PyTorch*

## Accuracy¶

The quality metrics were calculated on the SQuAD v1.1 dataset (“dev” split). Maximum sequence length is 384, maximum query length: 64, doc stride: 128, input is lower-cased.

Metric

Value

F1

92.60%

Exact match (EM)

86.36%

## Input¶

1. Token IDs, name: input_ids, shape: 1, 384. Sequence of tokens (integer values) representing the tokenized premise and question (“input_ids”). The sequence structure is as follows ([CLS], [SEP] and [PAD] should be replaced by corresponding token IDs as specified by the dictionary): [CLS] + tokenized question + [SEP] + tokenized premise of the question + [SEP] + ([PAD] tokens to pad to the maximum sequence length of 384)

2. Input mask, name: attention_mask, shape: 1, 384. Sequence of integer values representing the mask of valid values in the input (“input_mask”). The values of this input are are equal to:

• 1 at positions corresponding to the [CLS] + tokenized question + [SEP] + tokenized premise of the question + [SEP] part of the Token IDs (i.e. all positions except those containing the [PAD] tokens), and

• 0 at all other positions

3. Segment IDs, name: token_type_ids, shape: 1, 384. Sequence of integer values representing the segmentation of the Token IDs into question and premise (“segment_ids”). The values are equal to:

• 1 at positions corresponding to the tokenized premise of the question + [SEP] part of the Token IDs, and

• 0 at all other positions

## Output¶

1. Answer start, name: output_s, shape: 1, 384. Floating point-valued logit scores, where i-th value corresponds to the log-likelihood of the answer to the question starting at the i-th token position of the input.

2. Answer end, name output_e, shape: 1, 384. Floating point-valued logit scores, where i-th value corresponds to the log-likelihoods of the answer ending at i-th token position.

## Demo usage¶

The model can be used in the following demos provided by the Open Model Zoo to show its capabilities: