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--- |
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pipeline_tag: sentence-similarity |
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tags: |
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- sentence-transformers |
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- feature-extraction |
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- sentence-similarity |
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license: mit |
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--- |
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For more details please refer to our github repo: https://github.com/FlagOpen/FlagEmbedding |
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# BGE-M3 ([paper](https://arxiv.org/pdf/2402.03216.pdf), [code](https://github.com/FlagOpen/FlagEmbedding/tree/master/FlagEmbedding/BGE_M3)) |
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In this project, we introduce BGE-M3, which is distinguished for its versatility in Multi-Functionality, Multi-Linguality, and Multi-Granularity. |
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- Multi-Functionality: It can simultaneously perform the three common retrieval functionalities of embedding model: dense retrieval, multi-vector retrieval, and sparse retrieval. |
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- Multi-Linguality: It can support more than 100 working languages. |
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- Multi-Granularity: It is able to process inputs of different granularities, spanning from short sentences to long documents of up to 8192 tokens. |
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**Some suggestions for retrieval pipeline in RAG:** |
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We recommend to use following pipeline: hybrid retrieval + re-ranking. |
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- Hybrid retrieval leverages the strengths of various methods, offering higher accuracy and stronger generalization capabilities. |
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A classic example: using both embedding retrieval and the BM25 algorithm. |
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Now, you can try to use BGE-M3, which supports both embedding and sparse retrieval. |
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This allows you to obtain token weights (similar to the BM25) without any additional cost when generate dense embeddings. |
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- As cross-encoder models, re-ranker demonstrates higher accuracy than bi-encoder embedding model. |
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Utilizing the re-ranking model (e.g., [bge-reranker](https://github.com/FlagOpen/FlagEmbedding/tree/master/FlagEmbedding/reranker), [cohere-reranker](https://txt.cohere.com/rerank/)) after retrieval can further filter the selected text. |
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## News: |
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- 2/6/2024: We release the [MLDR](https://huggingface.co/datasets/Shitao/MLDR) (a long document retrieval dataset covering 13 languages) and [evaluation pipeline](https://github.com/FlagOpen/FlagEmbedding/tree/master/C_MTEB/MLDR). |
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- 2/1/2024: **Thanks for the excellent tool from Vespa.** You can easily use multiple modes of BGE-M3 following this [notebook](https://github.com/vespa-engine/pyvespa/blob/master/docs/sphinx/source/examples/mother-of-all-embedding-models-cloud.ipynb) |
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## Specs |
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- Model |
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| Model Name | Dimension | Sequence Length | Introduction | |
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|:----:|:---:|:---:|:---:| |
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| [BAAI/bge-m3](https://huggingface.co/BAAI/bge-m3) | 1024 | 8192 | multilingual; unified fine-tuning (dense, sparse, and colbert) from bge-m3-unsupervised| |
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| [BAAI/bge-m3-unsupervised](https://huggingface.co/BAAI/bge-m3-unsupervised) | 1024 | 8192 | multilingual; contrastive learning from bge-m3-retromae | |
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| [BAAI/bge-m3-retromae](https://huggingface.co/BAAI/bge-m3-retromae) | -- | 8192 | multilingual; extend the max_length of [xlm-roberta](https://huggingface.co/FacebookAI/xlm-roberta-large) to 8192 and further pretrained via [retromae](https://github.com/staoxiao/RetroMAE)| |
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| [BAAI/bge-large-en-v1.5](https://huggingface.co/BAAI/bge-large-en-v1.5) | 1024 | 512 | English model | |
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| [BAAI/bge-base-en-v1.5](https://huggingface.co/BAAI/bge-base-en-v1.5) | 768 | 512 | English model | |
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| [BAAI/bge-small-en-v1.5](https://huggingface.co/BAAI/bge-small-en-v1.5) | 384 | 512 | English model | |
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- Data |
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| Dataset | Introduction | |
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|:----:|:---:| |
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| [MLDR](https://huggingface.co/datasets/Shitao/MLDR) | Docuemtn Retrieval Dataset, covering 13 languages| |
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## FAQ |
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**1. Introduction for different retrieval methods** |
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- Dense retrieval: map the text into a single embedding, e.g., [DPR](https://arxiv.org/abs/2004.04906), [BGE-v1.5](https://github.com/FlagOpen/FlagEmbedding) |
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- Sparse retrieval (lexical matching): a vector of size equal to the vocabulary, with the majority of positions set to zero, calculating a weight only for tokens present in the text. e.g., BM25, [unicoil](https://arxiv.org/pdf/2106.14807.pdf), and [splade](https://arxiv.org/abs/2107.05720) |
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- Multi-vector retrieval: use multiple vectors to represent a text, e.g., [ColBERT](https://arxiv.org/abs/2004.12832). |
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**2. Comparison with BGE-v1.5 and other monolingual models** |
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BGE-M3 is a multilingual model, and its ability in monolingual embedding retrieval may not surpass models specifically designed for single languages. |
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However, we still recommend trying BGE-M3 because of its versatility (support for multiple languages and long texts). |
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Moreover, it can simultaneously generate multiple representations, and using them together can enhance accuracy and generalization, |
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unlike most existing models that can only perform dense retrieval. |
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In the open-source community, there are many excellent models (e.g., jina-embedding, colbert, e5, etc), |
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and users can choose a model that suits their specific needs based on practical considerations, |
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such as whether to require multilingual or cross-language support, and whether to process long texts. |
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**3. How to use BGE-M3 in other projects?** |
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For embedding retrieval, you can employ the BGE-M3 model using the same approach as BGE. |
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The only difference is that the BGE-M3 model no longer requires adding instructions to the queries. |
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For sparse retrieval methods, most open-source libraries currently do not support direct utilization of the BGE-M3 model. |
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Contributions from the community are welcome. |
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In our experiments, we use [Pyserini](https://github.com/FlagOpen/FlagEmbedding/tree/master/C_MTEB/MLDR#hybrid-retrieval-dense--sparse) and Faiss to do hybrid retrieval. |
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**Now you can ou can try the hybrid mode of BGE-M3 in [Vespa](https://github.com/vespa-engine/pyvespa/blob/master/docs/sphinx/source/examples/mother-of-all-embedding-models-cloud.ipynb |
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). Thanks @jobergum.** |
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**4. How to fine-tune bge-M3 model?** |
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You can follow the common in this [example](https://github.com/FlagOpen/FlagEmbedding/tree/master/examples/finetune) |
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to fine-tune the dense embedding. |
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Our code and data for unified fine-tuning (dense, sparse, and multi-vectors) will be released. |
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## Usage |
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Install: |
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``` |
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git clone https://github.com/FlagOpen/FlagEmbedding.git |
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cd FlagEmbedding |
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pip install -e . |
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``` |
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or: |
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``` |
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pip install -U FlagEmbedding |
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``` |
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### Generate Embedding for text |
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- Dense Embedding |
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```python |
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from FlagEmbedding import BGEM3FlagModel |
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model = BGEM3FlagModel('BAAI/bge-m3', |
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use_fp16=True) # Setting use_fp16 to True speeds up computation with a slight performance degradation |
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sentences_1 = ["What is BGE M3?", "Defination of BM25"] |
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sentences_2 = ["BGE M3 is an embedding model supporting dense retrieval, lexical matching and multi-vector interaction.", |
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"BM25 is a bag-of-words retrieval function that ranks a set of documents based on the query terms appearing in each document"] |
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embeddings_1 = model.encode(sentences_1, |
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batch_size=12, |
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max_length=8192, # If you don't need such a long length, you can set a smaller value to speed up the encoding process. |
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)['dense_vecs'] |
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embeddings_2 = model.encode(sentences_2)['dense_vecs'] |
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similarity = embeddings_1 @ embeddings_2.T |
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print(similarity) |
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# [[0.6265, 0.3477], [0.3499, 0.678 ]] |
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``` |
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You also can use sentence-transformers and huggingface transformers to generate dense embeddings. |
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Refer to [baai_general_embedding](https://github.com/FlagOpen/FlagEmbedding/tree/master/FlagEmbedding/baai_general_embedding#usage) for details. |
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- Sparse Embedding (Lexical Weight) |
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```python |
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from FlagEmbedding import BGEM3FlagModel |
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model = BGEM3FlagModel('BAAI/bge-m3', use_fp16=True) # Setting use_fp16 to True speeds up computation with a slight performance degradation |
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sentences_1 = ["What is BGE M3?", "Defination of BM25"] |
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sentences_2 = ["BGE M3 is an embedding model supporting dense retrieval, lexical matching and multi-vector interaction.", |
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"BM25 is a bag-of-words retrieval function that ranks a set of documents based on the query terms appearing in each document"] |
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output_1 = model.encode(sentences_1, return_dense=True, return_sparse=True, return_colbert_vecs=False) |
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output_2 = model.encode(sentences_2, return_dense=True, return_sparse=True, return_colbert_vecs=False) |
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# you can see the weight for each token: |
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print(model.convert_id_to_token(output_1['lexical_weights'])) |
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# [{'What': 0.08356, 'is': 0.0814, 'B': 0.1296, 'GE': 0.252, 'M': 0.1702, '3': 0.2695, '?': 0.04092}, |
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# {'De': 0.05005, 'fin': 0.1368, 'ation': 0.04498, 'of': 0.0633, 'BM': 0.2515, '25': 0.3335}] |
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# compute the scores via lexical mathcing |
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lexical_scores = model.compute_lexical_matching_score(output_1['lexical_weights'][0], output_2['lexical_weights'][0]) |
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print(lexical_scores) |
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# 0.19554901123046875 |
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print(model.compute_lexical_matching_score(output_1['lexical_weights'][0], output_1['lexical_weights'][1])) |
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# 0.0 |
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``` |
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- Multi-Vector (ColBERT) |
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```python |
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from FlagEmbedding import BGEM3FlagModel |
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model = BGEM3FlagModel('BAAI/bge-m3', use_fp16=True) |
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sentences_1 = ["What is BGE M3?", "Defination of BM25"] |
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sentences_2 = ["BGE M3 is an embedding model supporting dense retrieval, lexical matching and multi-vector interaction.", |
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"BM25 is a bag-of-words retrieval function that ranks a set of documents based on the query terms appearing in each document"] |
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output_1 = model.encode(sentences_1, return_dense=True, return_sparse=True, return_colbert_vecs=True) |
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output_2 = model.encode(sentences_2, return_dense=True, return_sparse=True, return_colbert_vecs=True) |
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print(model.colbert_score(output_1['colbert_vecs'][0], output_2['colbert_vecs'][0])) |
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print(model.colbert_score(output_1['colbert_vecs'][0], output_2['colbert_vecs'][1])) |
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# 0.7797 |
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# 0.4620 |
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``` |
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### Compute score for text pairs |
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Input a list of text pairs, you can get the scores computed by different methods. |
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```python |
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from FlagEmbedding import BGEM3FlagModel |
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model = BGEM3FlagModel('BAAI/bge-m3', use_fp16=True) |
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sentences_1 = ["What is BGE M3?", "Defination of BM25"] |
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sentences_2 = ["BGE M3 is an embedding model supporting dense retrieval, lexical matching and multi-vector interaction.", |
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"BM25 is a bag-of-words retrieval function that ranks a set of documents based on the query terms appearing in each document"] |
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sentence_pairs = [[i,j] for i in sentences_1 for j in sentences_2] |
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print(model.compute_score(sentence_pairs, |
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max_passage_length=128, # a smaller max length leads to a lower latency |
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weights_for_different_modes=[0.4, 0.2, 0.4])) # weights_for_different_modes(w) is used to do weighted sum: w[0]*dense_score + w[1]*sparse_score + w[2]*colbert_score |
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# { |
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# 'colbert': [0.7796499729156494, 0.4621465802192688, 0.4523794651031494, 0.7898575067520142], |
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# 'sparse': [0.195556640625, 0.00879669189453125, 0.0, 0.1802978515625], |
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# 'dense': [0.6259765625, 0.347412109375, 0.349853515625, 0.67822265625], |
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# 'sparse+dense': [0.482503205537796, 0.23454029858112335, 0.2332356721162796, 0.5122477412223816], |
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# 'colbert+sparse+dense': [0.6013619303703308, 0.3255828022956848, 0.32089319825172424, 0.6232916116714478] |
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# } |
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``` |
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## Evaluation |
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We compare BGE-M3 with some popular methods, including BM25, openAI embedding, etc. |
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- Multilingual (Miracl dataset) |
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- Cross-lingual (MKQA dataset) |
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- Long Document Retrieval |
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- MLDR: |
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Please note that [MLDR](https://huggingface.co/datasets/Shitao/MLDR) is a document retrieval dataset we constructed via LLM, |
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covering 13 languages, including test set, validation set, and training set. |
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We utilized the training set from MLDR to enhance the model's long document retrieval capabilities. |
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Therefore, comparing baselines with `Dense w.o.long`(fine-tuning without long document dataset) is more equitable. |
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Additionally, this long document retrieval dataset will be open-sourced to address the current lack of open-source multilingual long text retrieval datasets. |
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We believe that this data will be helpful for the open-source community in training document retrieval models. |
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- NarritiveQA: |
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- Comparison with BM25 |
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We utilized Pyserini to implement BM25, and the test results can be reproduced by this [script](https://github.com/FlagOpen/FlagEmbedding/tree/master/C_MTEB/MLDR#bm25-baseline). |
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We tested BM25 using two different tokenizers: |
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one using Lucene Analyzer and the other using the same tokenizer as M3 (i.e., the tokenizer of xlm-roberta). |
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The results indicate that BM25 remains a competitive baseline, |
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especially in long document retrieval. |
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## Training |
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- Self-knowledge Distillation: combining multiple outputs from different |
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retrieval modes as reward signal to enhance the performance of single mode(especially for sparse retrieval and multi-vec(colbert) retrival) |
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- Efficient Batching: Improve the efficiency when fine-tuning on long text. |
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The small-batch strategy is simple but effective, which also can used to fine-tune large embedding model. |
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- MCLS: A simple method to improve the performance on long text without fine-tuning. |
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If you have no enough resource to fine-tuning model with long text, the method is useful. |
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Refer to our [report](https://arxiv.org/pdf/2402.03216.pdf) for more details. |
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**The fine-tuning codes and datasets will be open-sourced in the near future.** |
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## Acknowledgement |
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Thanks the authors of open-sourced datasets, including Miracl, MKQA, NarritiveQA, etc. |
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Thanks the open-sourced libraries like [Tevatron](https://github.com/texttron/tevatron), [Pyserini](https://github.com/castorini/pyserini). |
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## Citation |
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If you find this repository useful, please consider giving a star :star: and citation |
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``` |
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@misc{bge-m3, |
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title={BGE M3-Embedding: Multi-Lingual, Multi-Functionality, Multi-Granularity Text Embeddings Through Self-Knowledge Distillation}, |
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author={Jianlv Chen and Shitao Xiao and Peitian Zhang and Kun Luo and Defu Lian and Zheng Liu}, |
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year={2024}, |
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eprint={2402.03216}, |
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archivePrefix={arXiv}, |
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primaryClass={cs.CL} |
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} |
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``` |
