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nigam@COLIEE-22: Legal Case Retrieval and Entailment Using Cascading of Lexical and Semantic-Based Models

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New Frontiers in Artificial Intelligence (JSAI-isAI 2022)

Part of the book series: Lecture Notes in Computer Science ((LNAI,volume 13859))

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Abstract

This paper describes our submission to the Competition on Legal Information Extraction/Entailment 2022 (COLIEE-2022) workshop on case law competition for tasks 1 and 2. Task 1 is a legal case retrieval task, which involves reading a new case and extracting supporting cases from the provided case law corpus to support the decision. Task 2 is a legal case entailment task, involving the identification of a paragraph from existing cases that entails the decision in a relevant case. We employed the neural models Sentence-BERT and Sent2Vec for semantic understanding and the traditional information retrieval model BM25 for exact matching in both tasks. As a result, our team (named “nigam”) ranked 5th among all the teams in Tasks 1 and 2. Experimental results indicate that the traditional information retrieval model BM25 still outperforms neural network-based models.

S. K. Nigam and N. Goel—These authors contributed equally to this work.

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Notes

  1. 1.

    https://github.com/ShubhamKumarNigam/COLIEE-22.

  2. 2.

    https://spacy.io/usage/linguistic-features#sbd.

  3. 3.

    https://en.wikipedia.org/wiki/Okapi_BM25.

  4. 4.

    https://github.com/dorianbrown/rank_bm25.

  5. 5.

    https://scikit-learn.org/stable/modules/generated/sklearn.feature_extraction.text.TfidfVectorizer.html.

  6. 6.

    https://github.com/epfml/sent2vec.

  7. 7.

    https://scikit-learn.org/stable/modules/generated/sklearn.metrics.pairwise.cosine_similarity.html.

  8. 8.

    https://www.sbert.net/.

  9. 9.

    https://www.sbert.net/docs/pretrained_models.html.

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Correspondence to Shubham Kumar Nigam .

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Nigam, S.K., Goel, N., Bhattacharya, A. (2023). nigam@COLIEE-22: Legal Case Retrieval and Entailment Using Cascading of Lexical and Semantic-Based Models. In: Takama, Y., Yada, K., Satoh, K., Arai, S. (eds) New Frontiers in Artificial Intelligence. JSAI-isAI 2022. Lecture Notes in Computer Science(), vol 13859. Springer, Cham. https://doi.org/10.1007/978-3-031-29168-5_7

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  • DOI: https://doi.org/10.1007/978-3-031-29168-5_7

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