transformers pytorch safetensors bart text2text-generation generated_from_trainer en dataset:Short-Answer-Feedback/saf_communication_networks_english arxiv:1910.13461 base_model:facebook/bart-large base_model:finetune:facebook/bart-large autotrain_compatible endpoints_compatible region:us
---
base_model: facebook/bart-large
datasets:
- Short-Answer-Feedback/saf_communication_networks_english
language: en
tags:
- generated_from_trainer
widget:
- text: 'Answer: In TCP there is a Sequence Number field to identify packets individually
    for reliability. There is no Sequence Number in UDP. The UDP header does not have
    an options field, while the TCP header does. In TCP there is an Advertised Window
    field for the Sliding Window Protocol for Flow Control. There is no Flow Control
    and therefore no Advertised Window field in UDP. In TCP there there is only a
    Data Offset field that specifies the header length. In UDP the whole Packet Length
    is transmitted. Reference: Possible Differences : The UPD header (8 bytes) is
    much shorter than the TCP header (20-60 bytes) The UDP header has a fixed length
    while the TCP header has a variable length Fields contained in the TCP header
    and not the UDP header : -Sequence number -Acknowledgment number -Reserved -Flags/Control
    bits -Advertised window -Urgent Pointer -Options + Padding if the options are
    UDP includes the packet length (data + header) while TCP has the header length/data
    offset (just header) field instead The sender port field is optional in UDP, while
    the source port in TCP is necessary to establish the connection Question: State
    at least 4 of the differences shown in the lecture between the UDP and TCP headers.'
---

# bart-finetuned-saf-communication-networks

This model is a fine-tuned version of [facebook/bart-large](https://huggingface.co/facebook/bart-large) on the [saf_communication_networks_english](https://huggingface.co/datasets/Short-Answer-Feedback/saf_communication_networks_english) dataset for Short Answer Feedback (SAF), as proposed in [Filighera et al., ACL 2022](https://aclanthology.org/2022.acl-long.587).

## Model description

This model was built on top of [BART](https://arxiv.org/abs/1910.13461), which is a sequence-to-sequence model trained with denoising as pretraining objective.

It expects inputs in the following format:
```
Answer: [answer] Reference: [reference_answer] Question: [question]
```

In the example above, `[answer]`, `[reference_answer]` and `[question]` should be replaced by the provided answer, the reference answer and the question to which they refer, respectively.


The outputs are formatted as follows:
```
[verification_feedback] Feedback: [feedback]
```

Hence, the `[verification_feedback]` label will be one of `Correct`, `Partially correct` or `Incorrect`, while `[feedback]` will be the textual feedback generated by the model according to the given answer.

## Intended uses & limitations

This model is intended to be used for Short Answer Feedback generation in the context of college-level communication networks topics. Thus, it is not expected to have particularly good performance on sets of questions and answers out of this scope.

It is important to acknowledge that the model underperforms when a question that was not seen during training is given as input for inference. In particular, it tends to classify most answers as being correct and does not provide relevant feedback in such cases. Nevertheless, this limitation could be partially overcome by extending the dataset with the desired question (and associated answers) and fine-tuning it for a few epochs on the new data.

## Training and evaluation data

As mentioned previously, the model was trained on the [saf_communication_networks_english](https://huggingface.co/datasets/Short-Answer-Feedback/saf_communication_networks_english) dataset, which is divided into the following splits.

| Split                 | Number of examples |
| --------------------- | ------------------ |
| train                 | 1700	             |
| validation            | 427	             |
| test_unseen_answers   | 375	             |
| test_unseen_questions | 479                |

Evaluation was performed on the `test_unseen_answers` and `test_unseen_questions` splits.

## Training procedure

The [Trainer API](https://huggingface.co/docs/transformers/main_classes/trainer#transformers.Seq2SeqTrainer) was used to fine-tune the model. The code utilized for pre-processing and training was mostly adapted from the [summarization script](https://github.com/huggingface/transformers/tree/main/examples/pytorch/summarization) made available by HuggingFace.

Training was completed in a little under 1 hour on a GPU on Google Colab.

### Training hyperparameters

The following hyperparameters were used during training:
- num_epochs: 8
- optimizer: Adam with betas=(0.9,0.999) and epsilon=1e-08
- learning_rate: 5e-05
- lr_scheduler_type: linear
- train_batch_size: 1
- gradient_accumulation_steps: 4
- eval_batch_size: 4
- mixed_precision_training: Native AMP
- seed: 42

### Framework versions

- Transformers 4.25.1
- Pytorch 1.12.1+cu113
- Datasets 2.7.1
- Tokenizers 0.13.2

## Evaluation results

The generated feedback was evaluated through means of the [SacreBLEU](https://huggingface.co/spaces/evaluate-metric/sacrebleu), [ROUGE-2](https://huggingface.co/spaces/evaluate-metric/rouge), [METEOR](https://huggingface.co/spaces/evaluate-metric/meteor), [BERTScore](https://huggingface.co/spaces/evaluate-metric/bertscore) metrics from HuggingFace, while the [accuracy](https://scikit-learn.org/stable/modules/generated/sklearn.metrics.accuracy_score.html) and [F1](https://scikit-learn.org/stable/modules/generated/sklearn.metrics.f1_score.html) scores from scikit-learn were used for evaluation of the labels.

The following results were achieved.

| Split                 | SacreBLEU | ROUGE-2 | METEOR | BERTScore | Accuracy | Weighted F1 | Macro F1 | 
| --------------------- | :-------: | :-----: | :----: | :-------: | :------: | :---------: | :------: |
| test_unseen_answers   | 36.0	    | 49.1    | 60.8   | 69.5      | 76.0     | 73.0        | 53.4     |
| test_unseen_questions | 2.4       | 20.1    | 28.5   | 36.6      | 51.6     | 41.0        | 27.9     |


The script used to compute these metrics and perform evaluation can be found in the `evaluation.py` file in this repository.

## Usage

The example below shows how the model can be applied to generate feedback to a given answer.

```python
from transformers import AutoModelForSeq2SeqLM, AutoTokenizer

model = AutoModelForSeq2SeqLM.from_pretrained('Short-Answer-Feedback/bart-finetuned-saf-communication-networks')
tokenizer = AutoTokenizer.from_pretrained('Short-Answer-Feedback/bart-finetuned-saf-communication-networks')

example_input = 'Answer: In TCP there is a Sequence Number field to identify packets individually for reliability. There is no Sequence Number in UDP. The UDP header does not have an options field, while the TCP header does. In TCP there is an Advertised Window field for the Sliding Window Protocol for Flow Control. There is no Flow Control and therefore no Advertised Window field in UDP. In TCP there there is only a Data Offset field that specifies the header length. In UDP the whole Packet Length is transmitted. Reference: Possible Differences : The UPD header (8 bytes) is much shorter than the TCP header (20-60 bytes) The UDP header has a fixed length while the TCP header has a variable length Fields contained in the TCP header and not the UDP header : -Sequence number -Acknowledgment number -Reserved -Flags/Control bits -Advertised window -Urgent Pointer -Options + Padding if the options are UDP includes the packet length (data + header) while TCP has the header length/data offset (just header) field instead The sender port field is optional in UDP, while the source port in TCP is necessary to establish the connection Question: State at least 4 of the differences shown in the lecture between the UDP and TCP headers.'
inputs = tokenizer(example_input, max_length=256, padding='max_length', truncation=True, return_tensors='pt')

generated_tokens = model.generate(
                inputs['input_ids'],
                attention_mask=inputs['attention_mask'],
                max_length=128
            )
output = tokenizer.batch_decode(generated_tokens, skip_special_tokens=True)[0]
```

The output produced by the model then looks as follows:

```
Correct Feedback: The response correctly identifies four differences between TCP and UDP headers. 
```

## Related Work

[Filighera et al., ACL 2022](https://aclanthology.org/2022.acl-long.587) trained a [T5 model](https://huggingface.co/docs/transformers/model_doc/t5) on this dataset, providing a baseline for SAF generation. The entire code used to define and train the model can be found on [GitHub](https://github.com/SebOchs/SAF).
